What is the test for determining whether medical malpractice contributed to the death of a patient?

treatment contributed to the victim's death. [Citations.] To be sure, when medical treatment is grossly improper, it may discharge liability for homicide if the maltreatment is the sole cause of death and hence an unforeseeable intervening cause. [Citations.] But here the record is devoid of any evidence of grossly improper treatment." (People v. Roberts, supra, 2 Cal.4th at p. 312.) The court held that there was no need to instruct the jury on a theory for which no evidence had been presented because the record failed to show that the treatment regimen constituted a supervening cause of death. (Id. at pp. 312-313.)