A jury on Thursday found three Santa Clara County jail deputies guilty of second-degree murder in the beating death of inmate Michael Tyree.
Jereh Lubrin, 30, Rafael Rodriguez, 28, and Matthew Farris, 28, could face life in prison for their convictions in the killing of bipolar 31-year-old Tyree on Aug. 26, 2015, the night before he was found dead in his cell with his spleen ruptured nearly in two.
"It's a sad day when law enforcement officers are convicted, when those sworn to uphold the law and protect others instead choose to victimize and, in this case, kill a mentally ill inmate," District Attorney Jeff Rosen said. "Without that protection, there is no law, there is no order, there is no justice, and in the end for Michael Tyree, there was no chance."
Santa Clara County Sheriff Laurie Smith also was at the courthouse and reacted to the verdict.
"The acts carried out by these three individuals have tarnished the reputation of this profession and of our entire agency," she said. "Conversely, I stand behind the hard work and dedication of the 1,400 deputies who perform their job every day."
The Tyree family attorney said the victim's relatives are grateful but not comforted.
"It's bittersweet because it's absolutely tragic," attorney Paula Canny said. "Michael's dead, and each of these three young men who ruined a guy's life now have ruined lives."
Jury deliberations began Thursday morning and were completed by late Thursday afternoon.
The jury hung on the charge of assault under color of authority in the case of 48-year-old Juan Villa, a second mentally ill inmate, the same night.
The defense had claimed that Tyree's death was not a homicide, suggesting that he died by suicide by jumping onto the corner of the sink in his cell, rupturing his organs.
The prosecution said the jail guards thrived on the abuse of their power over inmates.
According to witness testimony, the assault on Tyree began after he mouthed off to a nurse during "pill call," when medication is distributed to inmates.
Some former inmates said they saw all three deputies in Tyree's cell and that one of the deputies turned off the cell light when they left, which would have been unusual.
The defense attacked the inmates' testimony as inconsistent and accused some of them of being "professional witnesses" who believe their testimony could be rewarded with legal or immigration-related benefits, a claim that prosecutors have refuted.
Sentencing is scheduled for Sept. 1.
NBC Bay Area's Sergio Quintana contributed to this report.