What is the test for determining whether a fatal head injury was caused by multiple blunt force injuries to the head?

was caused by "multiple blunt force injuries to the head." As in People v. Blacksher (2011) 52 Cal.4th 769, 827, the autopsy photographs "depict cleaned wounds showing far less blood than photographs of the crime scene showing the position of the bodies." (See also People v. Garcia (2008) 168 Cal.App.4th 261, 294 [autopsy "photographs are clinical in appearance, consisting of close-up shots of the bullet wounds on the body" and "[n]one of the photographs depicts the victim's face or entire body"].)