¶1*1127Jennifer Brewer, argued, St. Louis, MO (Patrick J. Berrigan, Kansas City, MO, on the brief), for Appellant.
¶2Cassandra K. Dolgin, Asst. Atty. General, argued, Jefferson City, MO, for Appel-lee.
¶3Before BOWMAN and BEAM, Circuit Judges, and BOGUE,1 District Judge.
¶6Christopher Simmons was convicted in Missouri state court for the first degree murder of Shirley Crook and was sentenced to death. Simmons appeals from the district court’s denial of his petition for a writ of habeas corpus under 28 U.S.C. § 2254.
¶7Because we find the state court decisions involve neither an unreasonable application of federal law nor an unreasonable determination of the facts, we affirm.2
¶81. BACKGROUND
¶9On September 9, 1993, Shirley Crook was abducted from her home and murdered. Her face was covered with duct tape, her hands and feet were bound together, and she was thrown from a train trestle into the Meremac River. The cause of death was drowning.
¶10On September 10, 1993, after receiving information that Christopher Simmons had been involved in the murder, law enforcement officers from the Greater St. Louis Major Case Squad arrested Simmons at his high school and took him to the Fenton Police Department in Jefferson County, Missouri.
¶11Upon arrival at the department, three detectives took Simmons into an interview room. Detective Shane Knoll used an advice-of-rights form to read Simmons the warnings required by Miranda v. Arizona, 384 U.S. 436, 86 S.Ct. 1602, 16 L.Ed.2d 694 (1966). Simmons then signed a waiver and the detectives commenced interrogation. This initial interrogation lasted approximately two hours and was not electronically recorded.
¶12According to deposition and trial testimony by detectives, Simmons first denied any involvement in the crime. At various times, detectives moved within a foot of Simmons’ face and Detective Knoll raised his voice. The officers told Simmons that they thought he was lying. The detectives also suggested that Simmons’ accomplice had been arrested and was possibly confessing at that moment.
¶13Eventually, Simmons asked everyone but Knoll to leave the room. Simmons then made a statement and agreed to repeat it while being videotaped. At the beginning of the videotape, Knoll showed Simmons the advice-of-rights form and confirmed that the form had been read to *1128Simmons, that Simmons understood the form and had initialed and signed the Miranda waiver. Knoll then noted that the interrogation had been going on for approximately two hours, and the following exchange occurred:
MR. KNOLL: During the time all of this [interrogation] has been going on, you first started off saying you didn’t know nothing about this crime, and you didn’t want to tell us anything. Is that correct?
MR. SIMMONS: Yes.
MR. KNOLL: Since that time, after we continued to interview with you, you changed your mind, and you were willing to tell us the truth on exactly what took place on the main element of this crime. Is that correct?
MR. SIMMONS: Yes.
¶14During the videotaped interview, Simmons implicated himself and Charles Benjamin in the murder of Shirley Crook. Law enforcement officers also videotaped a re-enactment by Simmons at the crime scene.
¶15Before trial, defense counsel moved to suppress Simmons’ statements and, during trial, objected to testimony regarding the statement. His motion was denied and the objection was overruled.
¶16At trial, Detective Knoll testified to the content of the statement Simmons gave as a result of the September 10,1993, interrogation and described Simmons’ reenactment of the crime. His testimony demonstrates that in the early morning hours of September 9, 1993, seventeen-year-old Christopher Simmons and fifteen-year-old Charles Benjamin entered the home of Shirley and Steven Crook to burglarize it. They opened a back window that had been left cracked open to accommodate a garden hose, reached through, unlocked the door, and entered the Crook home.
¶17Once inside, Simmons turned on a hallway light, waking Mrs. Crook, who was home alone. Mrs. Crook sat up in bed and asked, “Who is there?” The two recognized one another from a traffic accident they had had in July of 1992. Simmons then entered her bedroom and ordered Mrs. Crook from her bed. When she did not comply he and Benjamin forced her to the floor. The two bound Mrs. Crook’s hands behind her back, taped her eyes and mouth shut, and placed her in the back of her minivan. Simmons drove the van from Mrs. Crook’s home in Jefferson County, Missouri, to a railroad trestle that spans the Meremac River in Castlewood State Park in St. Louis County, Missouri.
¶18After Simmons parked the van near the trestle, he and Benjamin began to remove Mrs. Crook from the van and discovered that she had freed her hands and had removed some of the duct tape from her face. They then covered her head with a towel, securing it with her bathrobe belt, and restrained her hands with her purse strap and feet with electrical wire they found on the bridge. After walking her to the trestle, they bound her hands to her feet. Simmons then pushed her off the bridge into the Meremac River.
¶19On redirect examination, Knoll testified that he did not know that Castlewood State Park existed or its location until Simmons led him there during the reenactment. Nor had he known other details of the murder that were later substantiated, such as that Shirley Crook’s feet were bound with electrical cable, until Simmons told him during the interrogation.
¶20The medical examiner testified that he identified Mrs. Crook’s body from her fingerprints. He determined that the cause of her death was drowning and noted that she had been conscious prior to being pushed from the bridge. The examiner also reported that Mrs. Crook had sustained several fractured ribs and considerable bruising and that those injuries did not result from her fall from the railroad trestle.
¶21Steven Crook, the victim’s husband, testified that he was employed by a carrier service and had been making an overnight *1129delivery on September 8, 1993. On the afternoon of September 9, 1993, upon discovering that his wife had not reported for work as she had planned, he returned home and found her missing. The bed clothes of their bed were in disarray, wads of duct tape were on the floor, and the couple’s dog, Chrissy, was lying on the bed with her nose and legs tangled in duct tape and whimpering. Mr. Crook then contacted the police to report Shirley missing.
¶22Friends of Simmons testified regarding statements Simmons had made prior to and after the murder. Christie Brooks testified that on the evening of September 8, 1993, Simmons told her he was planning to rob another house in the area — belonging to a man they had nicknamed “Voodoo” — on that night, and that Simmons had a ski mask, a dark button-up shirt with leather gloves taped to the sleeve, a small shotgun, and a large knife. He asked her for a gun because three people were to be involved and he only had two weapons.
¶23Brian Moomey, another friend of Simmons, testified that prior to the murder, Simmons and Benjamin talked about robbing a house and killing a family, that Simmons told Benjamin that “they could do it and not get charged for it because they [were] juveniles, and nobody would think that juveniles would do it.” Moomey also testified that, after the murder, Simmons bragged about killing a woman, that Moomey asked Simmons if he had killed the woman, and that Simmons said he had done so because she had seen his face.
¶24John Tessmer testified that, on several occasions prior to the murder of Shirley Crook, Simmons talked to him about a plan to murder the “voodoo guy” by throwing him off a bridge in order to get “a bunch of money.” Tessmer saw Simmons cutting masks from old sweatshirts and Simmons told him that the masks were for hiding their faces. Tessmer also testified that, while at Moomey’s house, Simmons tried to persuade him to go along with the plan to kill someone by throwing the victim off the bridge and that “they’d never think that kids did it.” On the evening of September 8, 1993, Simmons told Tessmer that he wanted to meet at Moomey’s house at 2:00 a.m. In the early morning hours of September 9, Simmons and Benjamin met at Moomey’s house. Tessmer went home.
¶25The defense cross-examined the prosecution’s witnesses at some length. In cross-examining Moomey and Tessmer, the defense highlighted their extensive criminal histories and their concerns that they may be suspects in the murder, and elicited inconsistencies between Moomey’s trial testimony and statements he had previously made to law enforcement officials.
¶26On June 16, 1994, in the Circuit Court of Jefferson County, a jury convicted Simmons of the first degree murder of Shirley Crook. During the penalty phase of the trial, members of Mrs. Crook’s family presented victim impact statements. In his penalty phase closing arguments, the prosecutor commented on Simmons’ age and what effect the jurors’ choice of penalty would have on his family.
¶27The jury found three statutory aggravating circumstances: (1) the murder was committed for the purpose of receiving money or any other thing of value; (2) the murder was committed for the purpose of avoiding, interfering with, or preventing a lawful arrest of the defendant; and (3) the murder involved depravityof mind, and as a result thereof, the murder was outrageously and wantonly vile, horrible, and inhuman. Tr. Trans, at 1163-64. Consequently, the jury imposed the death penalty. The trial court entered judgment against Simmons and sentenced him to be executed in accordance with Missouri law.
¶28Simmons sought post-conviction relief pursuant to Missouri Supreme Court Rule 29.15. After an evidentiary hearing, the court denied Simmons’ Rule 29.15 motion. Simmons then appealed the conviction, death sentence, and denial of the Rule 29.15 motion to the Missouri Supreme *1130Court. The Missouri Supreme Court affirmed.
¶29Simmons then filed a petition for writ of habeas corpus pursuant to 28 U.S.C. § 2254, raising fifteen grounds for relief, all of which the district court rejected. Although the district court issued a certificate of appealability on all fifteen claims, we quashed that certificate and granted a certificate on only three issues: (1) whether Simmons’ confession was voluntary; (2) whether victim impact testimony was constitutionally improper; and (3) whether the prosecutor’s closing arguments were constitutionally suspect.
¶30II. DISCUSSION
¶31We review the district court’s findings of fact for clear error and its conclusions of law de novo. Tokar v. Bowersox, 198 F.3d 1039, 1045 (8th Cir.1999). We apply a presumption of correctness to the state court’s findings of fact. Id.; 28 U.S.C. § 2254(e)(1).
¶32The Antiterrorism and Effective Death Penalty Act constrains the power of a federal habeas corpus court to grant a state prisoner’s application for a writ of habeas corpus on claims adjudicated on the merits in state court. Williams v. Taylor, 529 U.S. 420, 120 S.Ct. 1479, 1523, 146 L.Ed.2d 435 (2000); 28 U.S.C. § 2254(d)(1). The writ may issue only if the state-court adjudication either results in a decision “ ‘contrary to ... clearly established Federal law, as determined by the Supreme Court of the United States,’ ” or “ ‘involvefs] an unreasonable application of ... clearly established Federal law, as determined by the Supreme Court of the United States.’ ” Williams, 120 S.Ct. at 1523 (quoting 28 U.S.C. § 2254(d)(1)) (omission in original).
¶33Under the “contrary to” clause of section 2254(d)(1), “a federal habeas court may grant the writ if the state court arrives at a conclusion opposite to that reached by [the Supreme Court] on a question of law or if the state court decides a case differently than [the Supreme Court] has on a set of materially indistinguishable facts.” Id.A state court’s decision must be “mutually opposed” to clearly established Supreme Court precedent in order to satisfy the “contrary to” clause. Id. at 1519-20.
¶34“Under the ‘unreasonable application’ clause, a federal habeas court may grant the writ if the state court identifies the correct governing legal principle from [the Supreme Court’s] decisions but unreasonably applies that principle to the facts of’ the case before it. Id. at 1523. Therefore, “a federal habeas court may not issue the writ simply because that court concludes in its independent judgment that the relevant state-court decision applied clearly established federal law erroneously or incorrectly.” Id. at 1522. The state court’s application must also be unreasonable. Id.Whether a state court’s application was unreasonable is an objective inquiry. Id. at 1521.
¶35A. Voluntariness of Defendant’s Statement
¶36Simmons argues that his confession was obtained in violation of the Constitution because: (1) detectives threatened to use Simmons’ exercise of his right to remain silent against him; (2) detectives did not cease questioning him when he exercised his right to remain silent; (3) detectives promised him leniency to prompt his confession; and (4) because the totality of the circumstances rendered Simmons’ confession involuntary. A state court’s resolution of a factual question is entitled to a presumption of correctness, but a federal court must determine the ultimate legal question of the voluntariness of a confession. Evans v. Dowd, 932 F.2d 739, 741 (8th Cir.1991).
¶371. Threat to Use Defendant’s Silence Against Him
¶38In a deposition prior to trial, Knoll testified that, during the interrogation of Simmons, detectives “just told [Simmons] that if he chose to lie, which [Knoll] believed he *1131was, not to tell the truth, that if it went to court then [Knoll] would get on the stand and ... would testify that [Simmons] sat there during the whole interrogation, and denied his involvement in the case.” Simmons argues that Knoll’s statement constituted a threat to use his silence against him. The Missouri Supreme Court interpreted Knoll’s statement not as a threat to use Simmons’ silence against him, but instead as a threat to use his denial of involvement against him. We agree.
¶39Prior to a custodial interrogation, law enforcement officers must warn the person that he “has the right to remain silent” and “that anything he says can be used against him in a court of law.” Miranda v. Arizona, 384 U.S. 436, 479, 86 S.Ct. 1602, 16 L.Ed.2d 694 (1966). In the present case, Simmons was read his rights under Miranda. Knoll did not improperly threaten Simmons by telling him that if Simmons chose to lie, Knoll would testify as to what he said. Knoll merely restated the consequences of which Miranda warns: that Simmons’ statements of denial would be used against him. We reject the contention that use of statements of denial against a defendant would amount to use of a defendant’s silence against him.
¶402. Assertion of the Right to Remain Silent
¶41Once a person in custody has invoked his right to remain silent, law enforcement officers must scrupulously honor his assertion of that right. United States v. Cody, 114 F.3d 772, 775 (8th Cir.1997) (construing Michigan v. Mosley, 423 U.S. 96, 104, 96 S.Ct. 321, 46 L.Ed.2d 313 (1975)). However, to invoke one’s right to remain silent, one1 must unequivocally express his desire to remain silent. United States v.. Al-Muqsit, 191 F.3d 928, 936 (8th Cir.1999). An assertion of one’s Miranda rights must be neither ambiguous nor equivocal. See Davis v. United States, 512 U.S. 452, 459, 114 S.Ct. 2350, 129 L.Ed.2d 362 (1994) (applying this standard in determining whether a suspect had invoked his right to counsel). To determine whether a defendant has unequivocally invoked the right to remain silent, the defendant’s statements are considered as a whole. United States v. Johnson, 56 F.3d 947, 955 (8th Cir.1995). A denial of knowledge does not constitute an assertion of the right to remain silent. United States v. Turner, 551 F.2d 780, 782 (8th Cir.1977). More specifically, even statements by a juvenile that “he did not know the answer to a question put to him or that he could not, or would not, answer the question ... [are] not assertions of his right to remain silent.” Fare v. Michael C., 442 U.S. 707, 727, 99 S.Ct. 2560, 61 L.Ed.2d 197 (1979).
¶42In this case, Simmons failed to unambiguously or unequivocally assert his right to remain silent. In its analysis, the Missouri Supreme Court relied in part on Knoll’s trial testimony that Simmons had not sought to terminate the questioning. Yet Simmons focused the court’s attention on the beginning of Simmons’ videotaped statement where Knoll stated, “During the time all of this [interrogation] has been going on, you first started off saying you didn’t know nothing about this crime, and you didn’t want to tell us anything.” The Missouri Supreme Court found that, “[r]ead in context, Detective Knoll’s statement refers to Simmons’ initial denial of involvement in the crime, not any assertion of the Fifth Amendment right to remain silent.” State v. Simmons, 944 S.W.2d 165, 174 (Mo.1997) (en banc).
¶43We have reviewed the record and the videotaped interrogation, and we agree with the state court’s assessment. Although Simmons’ statements, as summarized by Knoll, are arguably susceptible to different interpretations, read in context, it is more plausible to interpret them as a denial of involvement than as an assertion of the right to remain silent. There has been no showing that Simmons ever clear*1132ly expressed his right to remain silent. Therefore, we find no error.3
¶443. Promises of Leniency and the Totality of the Circumstances
¶45Simmons argues that he was im-permissibly promised leniency in exchange for his statement and that his statement was involuntary under the totality of the circumstances. We consider these arguments together as the analysis of one informs that of the other. United States v. Larry, 126 F.3d 1077, 1079 (8th Cir.1997). Simmons argues that circumstances surrounding the interrogation rendered his statement involuntary. In support of his contention, he relies on the following: he was seventeen years old at the time; he was a poor student of below average intelligence; he was interrogated by three police officers for over two hours; law enforcement officials raised their voices while in close proximity to him, misrepresented to him that his accomplice was confessing, and reminded him that he was facing the death penalty while also telling him things would go better for him if he told the truth.
¶46We have carefully reviewed Simmons’ videotaped statement to police, along with transcripts of pretrial hearings on its admissibility, depositions of law enforcement officials, and the trial transcript. We find Simmons’ claim that his self-incriminating statement resulted from coercive activity is without merit. On videotape, Simmons acknowledged that his rights had been read to him and that he understood those rights but chose not to exercise them. He also acknowledged that he voluntarily chose to speak to law enforcement officials. Law enforcement officials testified that Simmons was read his Miranda rights before the officials began questioning him. Although the requirement that a Miranda warning be given does not dispense with the voluntariness inquiry, “ ‘[c]ases in which a defendant can make a colorable argument that a self-incriminating statement was “compelled” despite the fact that the law enforcement authorities adhered to the dictates of Miranda are rare.’” Dickerson v. United States, 530 U.S. 428, 120 S.Ct. 2326, 2336, 147 L.Ed.2d 405 (2000) (quoting Berkemer v. McCarty, 468 U.S. 420, 433 n. 20, 104 S.Ct. 3138, 82 L.Ed.2d 317 (1984)).
¶47To merit habeas corpus relief, Simmons must prove he involuntarily made his statement to law enforcement officials. Jenner v. Smith, 982 F.2d 329, 333 (8th Cir.1993). A statement is involuntary when it was extracted by threats, violence, or express or implied promises sufficient to overbear the defendant’s will and critically impair his capacity for self-determination. United States v. Pierce, 152 F.3d 808, 812 (8th Cir.1998). In applying this test, we look at the totality of the circumstances surrounding the interroga*1133tion, including law enforcement officials’ conduct and the defendant’s capacity to resist any pressure. Id.Specifically, we consider factors such as detention length, the repetitive and prolonged nature of questioning, and the accused’s age. Bramlett v. Lockhart, 876 F.2d 644, 646 (8th Cir.1989).
¶48We find that the questioning tactics in the present case were not improperly coercive. Officers may elicit statements by claiming not to believe the accused’s denials. Jenner, 982 F.2d at 334. Tactics such as deception and raised voices do not render a confession involuntary unless the overall impact of the interrogation caused the defendant’s will to be overborne. Id.Questioning a suspect for six or seven hours is not unconstitutionally coercive per se. Id.We do not find the period of interrogation in the present ease-approximately two hours-to be particularly lengthy. Cf. id.Furthermore, although it may have taken up to two hours for Simmons to make a statement implicating himself in the murder of Mrs. Crook, he waived his rights at the beginning of questioning and did not later assert them.
¶49Although a promise made by law enforcement is a relevant consideration in assessing police conduct, it is only one circumstance to be considered and does not render a confession involuntary per se. Larry, 126 F.3d at 1079; United States v. Kilgore, 58 F.3d 350, 353 (8th Cir.1995) (indicating that even if the suspect had been promised some form of leniency, this circumstance alone would not render his confession involuntary). The statement to an accused that telling the truth “would be better for him” does not constitute an implied or express promise of leniency for the purpose of rendering his confession involuntary. Bolder v. Armontrout, 921 F.2d 1359, 1366 (8th Cir.1990) (involving penalty of death); see, e.g., Pierce, 152 F.3d at 813 (statement that it would be to the suspect’s benefit if he cooperated with them is not improperly coercive); Bannister v. Armontrout, 4 F.3d 1434, 1440 (8th Cir.1993) (comments that it would be in the accused’s best interest to cooperate did not render his statement involuntary in death penalty case). Furthermore, “[a] truthful and non-coercive statement of the possible penalties which an accused faces may be given to the accused without overbearing one’s free will,” even when the accused is a minor. United States v. Ballard, 586 F.2d 1060, 1063 (5th Cir.1978).
¶50In the present case, the Missouri Supreme Court determined that, during the interrogation, Lt. Edward Robertson stepped into the room and told Simmons that he “was facing either the death penalty or life in prison and that it would be in his ‘best interest’ to tell the truth.” Simmons, 944 S.W.2d at 173. After Robertson exited, “Knoll and the other detectives encouraged Simmons to remember what Robertson had said and that it would be better for him to tell the truth.” Id.Simmons argues that, together, the statements constituted an implied promise of leniency. We agree with the state court, which found “this supposed nexus far too tenuous to support Simmons’ contentions.” Id. at 175.
¶51We recognize that courts have a duty to scrutinize juveniles’ statements with special care. Rone v. Wyrick, 764 F.2d 532, 534-35 (8th Cir.1985) (citing Haley v. Ohio, 332 U.S. 596, 599, 68 S.Ct. 302, 92 L.Ed. 224 (1948)). Statements by an accused juvenile must not be the product of “ ‘ignorance of rights or of adolescent fantasy, fright or despair’ ” in addition to not being coerced or suggested. Id. at 534 (quoting In re Gault, 387 U.S. 1, 55, 87 S.Ct. 1428, 18 L.Ed.2d 527 (1967)). Factors to consider in the totality-of-the-circumstances analysis involving a juvenile include the juvenile’s intelligence, maturity, and prior dealings with law enforcement. Id. at 535.
¶52Considering those factors, we cannot find that Simmons’ will was overborne by police tactics. Particularly compelling to *1134us is Simmons’ acknowledgment, on videotape, that he understood his rights and agreed that he had not been coerced by police officials. In the post-conviction relief proceedings, Dr. Daniel Cuneo—who had been hired by defense counsel prior to trial to investigate possible mitigating factors—testified that Simmons has a full-scale IQ of 88 and that he “was bright enough to do well in school if he had wanted. It wouldn’t have been easy, but he could have done it.” One of Simmons’ defense attorneys testified in the post-conviction relief proceedings that Simmons had previously been arrested as a suspect in a rape case. Simmons, therefore, was not unfamiliar with the criminal legal process.
¶53The facts of this case are less compelling than those presented in Sumpter v. Nix, 863 F.2d 563 (8th Cir.1988), where a special agent interrogated a suspect with an IQ of 89 for seven and one-half hours, suggested that the suspect’s wife would understand what had happened, and made implied promises of leniency and treatment for alcoholism if the suspect were to confess. Id. at 564-65. We concluded that the suspect’s will had not been overborne nor his capacity for self-determination critically impaired. Id. at 565. Simmons has similarly failed to show that his will was overborne and his capacity for self determination critically impaired. Law enforcement officials followed the dictates of Miranda and our totality-of-the-circumstances analysis convinces us that his waiver of rights and confession were not involuntary. His confession, therefore, satisfies constitutional scrutiny.
¶54B. Victim Impact Testimony
¶55Simmons asserts that penalty-phase testimony by Shirley Crook’s family4 constituted characterizations and opinions and, as such, were inadmissible under the Eighth Amendment and the Due Process Clause.
¶56During the sentencing phase, the state may offer evidence on personal *1135characteristics of the victim and the emotional impact of a crime on the victim’s family. Payne v. Tennessee, 501 U.S. 808, 827, 111 S.Ct. 2597, 115 L.Ed.2d 720 (1991); cf. id. at 833, 111 S.Ct. 2597 (O’Connor, J., concurring) (indicating that the Court did not reach the issue of whether the family’s opinions about the crime, the defendant, or the appropriate sentence are admissible). The Eighth Amendment does not bar, per se, relevant victim impact evidence or prosecutorial argument on the subject. Id. at 827, 111 S.Ct. 2597. Evidence relating to the victim is often already before the jury, at least in part, because of its relevance during the guilt phase of the trial. Id. at 823, 111 S.Ct. 2597. But even new relevant evidence may be admitted during the sentencing phase for the fact-finder to weigh. Id.Admission of victim impact evidence is limited only by the Due Process Clause of the Fourteenth Amendment in that such evidence may not be “so unduly prejudicial that it renders the trial fundamentally unfair.” Id. at 825, 111 S.Ct. 2597.
¶57The victim impact evidence at issue in the present case is not meaningfully distinguishable from that approved by the Supreme Court in Payne.5Here, as in Payne, the jury was unavoidably familiar with the facts of the murder of Shirley Crook. Based on the evidence presented during the guilt phase, the victim’s family added very little, if anything, to images of the murder that had already been planted in the jurors’ minds. The jury was free to weigh the victim impact testimony against other testimony. The victim impact testimony of Shirley Crook’s husband, daughter, and sister was no more inflammatory than the poignant testimony the Court found to have been properly admitted in Payne. In Payne, the prosecutor and victim’s mother gave voice to the impact on the victim’s child, while in the present case, the victim’s family members themselves spoke of the images that haunted them, the loss they suffered, and the coping mechanisms on which they relied.
¶58Given the evidence that had already been presented to the jury, we cannot say that admission of the victim impact testimony by Mrs. Crook’s family was so unduly prejudicial that it rendered the trial fundamentally unfair. Nor can we say that the testimony was either contrary to or unreasonably applied clearly established Supreme Court precedent. We, therefore, find the trial court committed no error in admitting the victim impact testimony.
¶59C. Prosecutor’s Penalty-Phase Closing
¶60Simmons further argues that the prosecutor’s penalty-phase closing argument deprived him of his constitutional rights. Specifically, he takes issue with comments that jurors should impose the death penalty for the benefit of his family and that his young age should not dissuade the jury *1136from imposing the death penalty.6 His claim regarding the prosecutor’s closing arguments presents both Eighth Amendment and due process issues.7
¶61The Eighth Amendment imposes a heightened need for “ ‘the responsible and reliable exercise of sentencing discretion’ in capital cases” and, therefore, a prosecutor’s closing argument must not diminish the jury’s sense of responsibility in imposing the death penalty. Antwine v. Delo, 54 F.3d 1357, 1362 (8th Cir.1995) (quoting Caldwell v. Mississippi, 472 U.S. 320, 329, 105 S.Ct. 2633, 86 L.Ed.2d 231 (1985)). “[I]t is constitutionally impermissible to rest a death sentence on a determination made by a sentencer who has been led to believe that the responsibility for determining the appropriateness of the defendant’s death rests elsewhere.” Caldwell, 472 U.S. at 328-29, 105 S.Ct. 2633. In Antwine, the prosecutor’s unfounded assurance that the defendant would be put to death instantaneously diminished the jury’s sense of responsibility and undermined the Eighth Amendment’s heightened requirement of reliability. Antwine, 54 F.3d at 1361, 1363. Similarly, in Caldwell, the prosecutor improperly urged the jury to believe that, if it imposed the death penalty, it would not actually be responsible for determining whether the defendant would die because a death sentence would ultimately be reviewed for correctness by an appellate court. Caldwell, 472 U.S. at 323, 105 S.Ct. 2633. The prosecutor, thereby, undermined the responsible and reliable exercise of sentencing discretion in violation of the Eighth Amendment. Id. at 328-29, 105 S.Ct. 2633.
¶62In the present case, although we find the prosecutor’s closing sprinkled with improper comments,8 the prosecutor’s remarks did not diminish the jury’s sense of responsibility. Unlike the comments made by prosecutors in Antwine and Caldwell, here, the prosecutor’s closing argument did not dilute the gravity of a death sentence or place the responsibility of imposing a capital sentence in hands other than those of the jurors. We find that the district court did not err in rejecting Simmons’ Eighth Amendment claim.
¶63Simmons also asserts that the improper comments violated his due process rights. Under due process analysis, it is not enough that a prosecutor’s remarks were undesirable or even universal*1137ly condemned, but they must have so infected the hearing with unfairness so as to deny the defendant of due process. See Darden v. Wainwright, 477 U.S. 168, 181, 106 S.Ct. 2464, 91 L.Ed.2d 144 (1986) (addressing closing arguments during the guilt-innocence phase of the trial). Not only must the prosecutor’s comments be improper, they must also be prejudicial. Therefore, upon finding that a prosecutor has made improper comments in his closing argument, we: (1) measure the type of prejudice emanating from the argument; (2) examine what defense counsel did in his argument to minimize the prejudice; (3) review jury instructions to determine if the jury was properly instructed; and (4) determine if there is a reasonable probability that the outcome of the sentencing phase would have been different in light of all the aggravating and mitigating circumstances. Antwine, 54 F.3d at 1363.
¶64In the present case, the prosecutor’s comments that jurors should “show some mercy to [Simmons’] family [and] give him death” are analogous to those we condemned in Antwine.9 On cross-examination during the penalty phase, the prosecution elicited testimony from Simmons’ ten-year-old brother that he looked up to his brother.10 We find improper, not to mention illogical, the prosecutor’s suggestion that the jury should impose the death penalty to “[s]pare those kids” of growing up to be like Simmons. We admonish the prosecutor to consider the implications of placing the burden of an execution on the shoulders of a child, even if that burden exists only in the child’s mind or in prose-cutorial rhetoric. Reiterating what we said in Antwine, such comments have “no place in an American courtroom.” 54 F.3d at 1363. There is “ ‘no legal or ethical justification for imposing the death penalty on this basis and it is not a proper factor to be considered by the jury, for it does not reflect the properly considered circumstances of the crime or the character of the individual.’” Id. at 1364 (quoting Blair v. Armontrout, 916 F.2d 1310, 1323 (8th Cir.1990)).
¶65Likewise, we condemn the prosecution for teetering on the edge of misstating the law with regard to the significance of Simmons’ age as a mitigating factor. Both the Eighth and Fourteenth Amendments prohibit precluding considering age as a mitigating factor, and the chronological age of a minor is a “relevant mitigating factor of great weight.” Eddings v. Oklahoma, 455 U.S. 104, 110, 116, 102 S.Ct. 869, 71 L.Ed.2d 1 (1982). With that said, we recognize that the sentencer ultimately determines the weight to be given relevant mitigating evidence and is merely prohibited from giving it no weight by excluding it from consideration. Id. at 114-15, 102 S.Ct. 869. In Eddings, the trial and appellate courts refused to consider certain mitigating circumstances. Id.In contrast, jurors in the present case were not precluded from considering Simmons’ age and, therefore, the prosecutor’s comments did not violate the Eighth Amendment. They were, however, improper.
¶66Although we find the prosecution’s statements to be improper, we are unable to find that the offending comments prejudiced Simmons. First, with regard to the type of prejudice, the prosecutor’s comments were not so egregious that they would “undermine the jury’s sense of responsibility and its individualized consideration of the defendant.” Antwine, 54 F.3d *1138at 1364. Nor were they combined with comments already determined to violate the Constitution, as was the case with comments regarding the defendant’s family in Antwine. Id.The prosecution’s arguments regarding the defendant’s youthful age addressed the weight of that mitigating circumstance but did not preclude the jury from considering it. In addition, during the guilt phase, witnesses testified that Simmons had included his youth in his risk calculations prior to killing Mrs. Crook, thus bringing age into play for the purpose of closing argument. The prosecutor’s comments about Simmons’ age were of the same tenor as the properly presented evidence. Furthermore, unlike Antwine, in the present case there is no Eighth Amendment violation to “bolster a finding of a due-process violation.” Id.; see also Newlon v. Armontrout, 885 F.2d 1328, 1337 (8th Cir.1989).
¶67Second, although defense counsel did not object to the prosecution’s arguments, he made significant efforts to minimize prejudice the comments may have caused. Counsel focused a substantial portion of his closing argument on stressing that Simmons’ youth “should make a huge difference” in the jury’s decision-making process and specifically addressed the prosecutor’s age-related arguments. With regard to the prosecution’s comments to spare Simmons’ family by imposing the death penalty, we look at the defense counsel’s opening summation to determine the effect of the comments on the sentencing as a whole. See Darden, 477 U.S. at 182, 106 S.Ct. 2464 (addressing the prosecutor’s closing argument during the guilt stage). Albeit unartfully, the prosecutor was responding to the defense counsel’s plea to the jury to “give [Simmons] a life sentence for his family[’s benefit].” Furthermore, although the prosecutor’s argument that jurors would be showing mercy to Simmons’ family by sentencing him to death is illogical, defense counsel further undermined the argument by presenting testimony by Simmons’ family that clearly demonstrated imposing the death penalty on their loved one would not amount to showing them mercy. Defense counsel’s presentation of testimony favorable to Simmons by family members themselves, his persistent appeal to jurors’ consciences, as well as his concentration on jury instructions favorable to Simmons, effectively countered any prejudice the prosecutor’s comments may have caused.
¶68Third, the jury was properly instructed that it was free to consider age as a mitigating factor, that the attorneys’ arguments were not evidence, and that the jury should govern its deliberations based on the laws provided in the instructions, the evidence, and reasonable inferences drawn therefrom. The jury instructions explicitly limited the aggravating circumstances the jury could consider. The jury was also instructed that it was “not compelled to fix death as the punishment even if [jurors did] not find the existence of one or more mitigating circumstances sufficient to outweigh the aggravating circumstances which [it] found to exist.” Defense counsel vigorously stressed that the jury should apply the mitigating factors to Simmons’ benefit.
¶69Finally, taking into consideration the aggravating and mitigating circumstances, we find no reasonable probability that the outcome of the sentencing phase would have been different had the prosecution not made its improper comments. See Preston v. Delo, 100 F.3d 596, 602 (8th Cir.1996) (disapproving of the prosecutor’s argument as “mean-spirited and unnecessary,” but concluding that the comments presented no reasonable probability that the statement more than minimally affected the outcome of the sentencing phase). The trial court limited the aggravating circumstances the jury could consider to four. The jury found three of those statutorily-defined aggravating circumstances.11 It *1139gave no indication that it considered Simmons’ age or the effects on his family as aggravating circumstances. It was given wide latitude to sentence Simmons to life even if it found no mitigating circumstances. Looking at the sentencing phase as a whole, we do not find it reasonably probable that the jury would have decided to impose a life sentence rather than death but for the prosecutor’s improper comments.12
¶70We cannot say that the prosecutor’s closing arguments at the sentencing stage of the trial rendered Simmons’ sentence fundamentally unfair or deprived him of the reliability the Eighth Amendment requires.
¶71III. CONCLUSION
¶72Accordingly, the order of the district court dismissing the petition is affirmed.