Murder of the first degree may be mitigated by any of the following circumstances, even though the mitigating circumstance is not sufficient to constitute a defense or reduce the degree of the crime:
1. The defendant has no significant history of prior criminal activity.
2. The murder was committed while the defendant was under the influence of extreme mental or emotional disturbance.
3. The victim was a participant in the defendant’s criminal conduct or consented to the act.
4. The defendant was an accomplice in a murder committed by another person and the defendant’s participation in the murder was relatively minor.
5. The defendant acted under duress or under the domination of another person.
6. The youth of the defendant at the time of the crime.
7. Any other mitigating circumstance.