Sgt. Paul Henry said Sonoma County pathologist Dr. Kelly Arthur reviewed the report of an independent pathologist hired by the Zhou family and she stands by her conclusion that there was no foul play or trauma evident during her autopsy. All evidence points to suicide, Henry said.
Zhou's father Yitong Zhou has insisted his daughter was murdered. He said a second autopsy in May 2007 by a pathologist hired by his family concluded his daughter suffered multiple blunt force trauma.
Yitong Zhou did not immediately return a call for comment late Wednesday afternoon, on the police department's conclusion of the investigation.
The 23-year-old student was found dead in the trunk of her 2006 Toyota Corolla that was discovered in a parking lot at Santa Rosa Junior College on Jan. 25, 2007.
Santa Rosa police said three empty bottles of Unisom sleeping pills were found next to her body.
In February 2007, Sonoma County coroner's Sgt. Mitch Mana said toxicology tests revealed the presence of diphenhydramine, a prime ingredient in the antihistamine Benadryl, a sleep aid available without a prescription. Mana said the level of the drug found in Zhou's body was "potentially toxic." The autopsy also found no acidic, neutral or basic drugs or ethyl alcohol in her system.
Henry would not comment on the details or conclusion of the autopsy report provided by the Zhou family.
"There are some differences in the two findings," Henry said.
The autopsy arranged by the Zhou family was conducted two months after Zhou's death and the Sonoma County coroner's office autopsy was the day after her death, Henry said.