A forensic pathologist took the stand Thursday to back up testimony from the doctor who performed the autopsy on Thomas.
Video of the violent run-in between Fullerton police and Thomas provides compelling evidence that Thomas died from "prolonged mechanical chest compression and blunt facial injuries", said Dr. Anthony Juguilon, Orange County's chief forensic pathologist.
His findings back up Dr. Aruna Singhania's testimony. Sinhania, who performed the autopsy, found that the altercation deprived oxygen to the brain.
Juguilon, who said he has performed about 6,500 autopsies in his career, said that the weight police applied to restrain Thomas restricted his breathing, making it harder for him to get oxygen into his system, which led to brain and organ failure.
The defense, however, says Thomas had a weak diseased heart caused by years of methamphetamine use and likely suffered heart failure during the struggle that involved former Fullerton police officer Manuel Ramos and former Cpl. Jay Cicinelli.
Ramos is on trial for second degree murder and Cicinelli is charged with involuntary manslaughter and excessive force.
Away from the jury, prosecutors filed a motion seeking confidential personnel records from the Fullerton Police Department to try to impeach the credibility of an earlier defense witness who trained Ramos and Cicinelli.
Fullerton Cpl. Stephen Rubio testified the video showed officers acted within department policy, although Ramos' use of profanity may have been a "slight" policy violation.
Prosecutors allege Ramos sparked the violent confrontation with a verbal threat. The defense says the officers were doing their jobs, faced with someone who repeatedly failed to follow orders.
In a statement from a 2011 police report made public for the first time and attached to the prosecutors' motion Thursday, Ramos wrote "it took all his strength" to hold down Thomas' feet as other officers tried to handcuff him.
"I was shocked by his strength ... I was in fear that if I allowed Thomas to regain his footing, or unable to get him handcuffed, he was going to hurt me or Officer Wolfe," said
Ramos and former Officer Joseph Wolfe, who was later charged, were the first to encounter Thomas near the bus depot in Fullerton as they investigated a report of someone trying to break into cars.
Six officers eventually responded, including Cicinelli who said in his police report that he Tasered Thomas but he continued to fight and tried to grab his Taser. That's when he struck Thomas in the face and head with it.
By the time he was handcuffed, Thomas was bloody and never regained consciousness.
Jurors have the next two weeks off for the holidays. The trial will resume Jan. 6.