For months, the Alameda County sheriff's deputies allowed a high-security inmate to leave his cell at the Santa Rita Jail without handcuffs or waist restraints.
They'd give him access to other inmates in one-person cells, prosecutors said, by unlocking the doors or the small slots through which they are handcuffed. Then, armed with a shampoo bottle or plastic tub filled with urine and feces, he'd strike, spraying the contents onto the inmates.
Between summer and fall of last year, prosecutors say, four deputies facilitated those "gassing" attacks on several inmates.
Prosecutors this week filed felony charges against the deputies in connection with the brutal attacks, marking the latest in a series of abuse scandals that have rocked California jails in recent years and triggered widespread calls for reforms.
Alameda County Dist. Atty. Nancy O'Malley, in a statement, called the attacks "sadistic and terrorizing acts."
"There is no rational explanation for their actions aside from abject cruelty and a disregard for the humanity of the inmates," she said.
One deputy, Erik McDermott, 27, is also accused of choking an inmate until he fell unconscious.
Prosecutors said he and Deputy Justin Linn, 24, tried to intimidate a witness from speaking with investigators when they asked another inmate to inform the witness' gang that he was a snitch, according to a complaint filed in Alameda County Superior Court.
According to the complaint, the pair searched the witness' cell, and Linn wrote up a report recommending the inmate be disciplined.
Both deputies were charged with assault by a public officer — Linn was charged with four counts, and McDermott was charged with two — and one count each of dissuading a witness by force or threat and conspiracy to obstruct justice, the complaint said.
Deputies Sarah Krause, 26, and Stephen Sarcos, 30, were each charged with one count of assault by a public officer.
Attorneys representing the deputies could not be reached for comment Wednesday.
A lengthy investigation began after jail employees told supervisors in January about the alleged abuse. The four deputies were pulled from duty soon after.
Authorities interviewed more than 40 people, including Alameda County Sheriff's Office employees and inmates in the county jail and various state prisons.
Sarcos quit the Sheriff's Office during the investigation. The three other deputies remain on paid leave, according to Alameda County Sheriff's Sgt. Ray Kelly.
Charging documents revealed details about how the attacks unfolded.
In one incident, an inmate said he was awakened when someone unlocked his cell door, allowing another inmate to throw urine on him, according to a probable cause statement attached to the complaint.
When the inmate pressed the emergency call button to report the incident, he told investigators, Linn responded to his cell and laughed at him, the document said.
The inmate involved in staging the attacks said the deputies opened cell doors or handcuffing slots for him so he could carry them out, the document said.
All four deputies were arrested last week and freed after posting bail. They appeared this week in court, where a judge increased Linn and McDermott's bail amounts from $135,000 to more than $300,000 each. Sarcos and Krause had each posted $35,000 bail.
They are scheduled to be arraigned Monday.
The case prompted agency officials to review internal policies, Kelly said, and a plan is in the works to install video cameras "everywhere we can put them within the facility."
In Los Angeles County, a jail abuse probe led to convictions of more than 20 Sheriff's Department officials — including former Sheriff Lee Baca — accused of abusing inmates, some of whom were mentally ill, or of obstructing federal investigators looking into jail violence.
In San Bernardino County, dozens of inmates accused deputies in a series of federal lawsuits of stunning them with Tasers while they delivered meals to other inmates or jerking their handcuffed wrists above their heads, sometimes at gunpoint, in a move called "chicken winging."
In July, 32 current and former inmates at the West Valley Detention Center in Rancho Cucamonga settled five federal lawsuits against San Bernardino County and the San Bernardino County Sheriff's Department for $2.5 million.
Sept. 6, 8:45 p.m.: This article was updated throughout with additional details.