¶1The defendant appeals from his conviction of operating a motor vehicle under the influence of alcohol, third offense.
¶2The defendant was authorized six peremptory challenges. Prior to commencement of the defendant’s trial, the trial judge conducted individual voir dires of the venire to inquire whether *712the prospective jurors, their families, or their close friends had personal or professional relationships with any of the witnesses. During the individual voir dires, the defendant exercised three of his peremptory challenges. When one prospective juror (Juror X) was called, she stated that she knew the names of town police officers who would be testifying during the trial, probably because she lived in a very small town. The defendant attempted to challenge Juror X for cause. The judge accordingly inquired of Juror X to determine whether she could remain impartial. He concluded that she was indifferent, and seated her. The individual voir dires continued until the remaining jurors were seated.
¶3Upon the jurors’ return from lunch, and before they were sworn, the prosecutor revealed to the judge that he had discovered that Juror X had a closer relationship with one of the Commonwealth’s police witnesses than previously discussed, more than just mere acquaintance from living in the same small town. It was revealed that the arresting officer, Officer Mousseau, had been a tenant of Juror X’s in-laws (Juror X’s husband’s brother and the brother’s wife) and that Officer Mousseau’s wife was currently working for Juror X’s in-laws.
¶4The defendant contends the trial judge abused his discretion in disallowing him use of the peremptory challenge. We agree.
¶5Under Mass.R.Crim.P. 20(c)(2), 378 Mass. 891 (1979), a peremptory challenge “shall be made before the jurors are sworn and may be made after the determination that a person called to serve as a juror stands indifferent in the case.” See Commonwealth v. Johnson, 426 Mass. 617, 626-627 (1998). A judge’s erroneous disallowance of a peremptory challenge is reversible error even without a showing of prejudice. Commonwealth v. Wood, 389 Mass. 552, 564 (1983). Commonwealth v. Somers, 44 Mass. App. Ct. 920, 922 (1998).
¶6The only pertinent issue here is whether the judge’s disallowance of defense counsel’s challenge was based on defense counsel’s failure to comply with Mass.R.Crim.P. 20(c)(2),
¶7*714Accordingly, the judgment is reversed, the verdict is set aside, and the case is remanded for further proceedings.
¶8So ordered.
¶9See G. L. c. 90, § 24.
¶10Twelve jurors and two alternates were selected. Juror X was juror number eight.
¶11The in-laws owned a child daycare center in which Officer Mousseau’s wife was working.
¶12We note that at the time the judge conducted the first individual voir dire of Juror X and found her indifferent, defense counsel did not have knowledge of Juror X’s relationship to Officer Mousseau. However, the record reveals that defense counsel, after learning of the relationship, stated that if he had known of that relationship at the time of the first individual voir dire, he would have exercised his peremptory challenge to exclude her.
¶13The judge stated, “Well, I understand you might have chosen to exercise your right to challenge, but because the juror in my view did not conceal information, because I don’t believe the questions I asked should have elicited this information, I don’t believe the juror has concealed anything and therefore I’m not going to be opening the issue.”
¶14As there was no insinuation that defense counsel’s exercise of his peremptory challenge was motivated by discrimination against a member in a discrete group, such as a race, see generally Brown, McGuire & Winters, The Peremptory Challenge as a Manipulative Device in Criminal Trials: Traditional Use or Abuse, 14 New Eng. L. Rev. 192 (1978), Juror X’s relationship to the case needed only to raise a spectre of individual bias to serve as a basis for peremptory challenge. See Commonwealth v. Soares, 377 Mass. 461, 485 (1979); Commonwealth v. Maldonado, 439 Mass. 460, 463 (2003).