In People v. Humphrey (1996) 13 Cal.4th 1073, the evidence not only showed a long history of abuse between the defendant and the victim, it revealed the victim had actually threatened to kill the defendant and shot at her the day before the killing occurred. (Humphrey, supra, 13 Cal.4th at pp. 1078-1080.) There was also evidence that the victim had threatened to kill the defendant and reached for a gun just moments before the killing took place. (Ibid.) Thus, from an objective standpoint, there was substantial evidence of imminent peril to the defendant. In addition, the defendant testified to her belief that if she didn't grab the gun and shoot the victim, the victim was going to shoot her first. (Id. at p. 1080.) Under these circumstances, the failure to allow expert testimony on BPS was deemed prejudicial because it could have established the reasonableness of the defendant's beliefs, as articulated in her testimony and corroborated by the other evidence in the case. (Id. at pp. 1089-1090.)