Alameda County sheriff's officials said three current deputies and one former deputy were arrested Thursday for allegedly mistreating inmates at the Santa Rita Jail in Dublin.
The deputies allegedly facilitated and allowed an inmate to throw bodily fluids, including feces and urine, onto other inmates housed in a maximum security unit of the jail, according to the sheriff's office.
Sheriff's officials said staff at Santa Rita brought the allegations of misconduct to their attention in January and they conducted an investigation that focused on incidents at the jail between the summer and fall of 2016.
The four people arrested Thursday are Sarah Krause, Justin Linn, Erik McDermott and Stephen Sarcos.
Sheriff's spokesman Sgt. Ray Kelly said Krause, Linn and McDermott have been placed on administrative leave and Sarcos has resigned.
Kelly said bail for Linn and McDermott has been set at $135,000 and bail for Krause and Sarcos has been set at $35,000.
Sheriff's officials said they determined that the allegations were criminal in nature and Sheriff Gregory Ahern assigned the investigation to detectives at the Eden Township Substation in San Leandro.
More than 40 people were interviewed during the investigation, including sheriff's office employees, Alameda County inmates and inmates at various state prisons.
Sheriff's officials said they also met with members of the Alameda County District Attorney's Office to advise them of the alleged criminal behavior.
Sheriff's officials said Linn and McDermott were arrested on suspicion of intimidation of a witness and assault under the color of authority.
They said Krause and Sarcos were arrested for assault under the color of authority for a single incident in the fall of 2016.
Ahern said in a statement that he is "deeply disturbed and saddened" by the alleged misconduct and criminal behavior.
"Only these four individuals are identified as involved in this criminal activity. We have sought charges against the four individuals and they must now answer to these allegations," Ahern said.
"Although these allegations are egregious and shocking, the actions of these four individuals do not reflect the dedication and professionalism of the 1,600 employees who work at the Alameda County Sheriff's Office," he said.
"I am very proud of the employees who came forward to disclose this behavior. I also commend the inmates in our custody for their assistance," Ahern said.
Kelly said the district attorney's office will file charges against the four current and former employees but prosecutors weren't immediately available to confirm if charges have been filed or say when the four might appear in court.