In this section the following words have the meanings indicated. “Battered Spouse Syndrome” means the psychological condition of a victim of repeated physical and psychological abuse by a spouse, former spouse, cohabitant, or former cohabitant which is also recognized in the medical and scientific community as the “Battered Woman’s Syndrome”. “Defendant” means an individual charged with: First degree murder, second degree murder, manslaughter, or attempt to commit any of these crimes; or Assault in the first degree. Notwithstanding evidence that the defendant was the first aggressor, used excessive force, or failed to retreat at the time of the alleged offense, when the defendant raises the issue that the defendant was, at the time of the alleged offense, suffering from the Battered Spouse Syndrome as a result of the past course of conduct of the individual who is the victim of the crime for which the defendant has been charged, the court may admit for the purpose of explaining the defendant’s motive or state of mind, or both, at the time of the commission of the alleged offense: Evidence of repeated physical and psychological abuse of the defendant perpetrated by an individual who is the victim of a crime for which the defendant has been charged; and Expert testimony on the Battered Spouse Syndrome.