Three correctional officers were placed on leave after an inmate’s death at Santa Clara County’s Main Jail last weekend, raising concerns about excessive use of force behind bars.

The maximum-security inmate—identified as 31-year-old Michael Tyree—died in his sixth-story cell after a routine check-in around midnight Aug. 27. According to news reports, he was serving a five-day sentence for petty theft and had a history of mental illness.

Sheriff's Office spokesman Sgt. James Jensen originally said that correctional officers found the inmate unresponsive and entered his cell to revive him. But the story changed when sources told the Mercury News and NBC Bay Area that the guards might have had a hand in the man’s death.

Community civil rights groups criticized officials for being slow to release details about the incident, which was caught on video. An criminal investigation and autopsy are underway.

According to the Merc, jail guards aggressively restrained the inmate and failed to report the confrontation until someone else found his body a half hour later. The newspaper later identified the guards as Jereh Lubrin, Matthew Farris and Rafael Rodriguez. Investigators reportedly served search warrants at their homes over the weekend.

Tyree had a long history of mental health issues, according to NBC Bay Area. Jail officials planned to transfer him to a bed at Momentum Crisis Residential Treatment Center, a nonprofit mental health clinic. The TV news station cited sources claiming that the inmate suffered wounds consistent with a blunt force beating.

Jail watchdogs said problems typically arise between guards and inmates with special needs—especially those with mental illness.

In a federal lawsuit filed against jail officials this summer, an inmate named Shane Miller alleges violations of the Americans with Disability Act and seeks punitive damages. The case names deputies David Pearce, Jose Chacon, John Chetcuti, Jason Dias, Mario Tejeda and Ramon Madriz and some of their command staff as defendants.

The lawsuit says jail guards failed at various times to accommodate Miller’s disability, which renders him unable to support his own weight. The complaint cites an instance in June 2014 when he was unable to hoist himself up to comply with orders to gather his things and move to a new cell.

“When Miller failed to rise because he was unable to do so, officers Pearce and Dias applied twist locks on his hands and arms and raised him up and into a wheelchair,” according to the complaint, “causing Miller to scream in pain.”

The following month, Miller—too weak to lift himself onto the toilet—said he was lying in his own urine and feces when Deputy Chacon ordered him to stand. Miller told him he couldn’t get up. Chacon allegedly pepper sprayed him for failing to comply.

Guards then cuffed Miller’s hands and feet to a restraint chair, the complaint continues, took him to the sun deck, doused him in water and left him to dry.

Earlier this year—on Jan. 3—Miller said he was lying on his cell floor when Deputy Tejeda arrived for a “welfare check.” Per the complaint, the officer kicked the inmate “on his back near his kidneys with sufficient force to cause Miller’s head to slam against the concrete wall.”

Sgt. Jensen—who’s also named in the lawsuit—declined to comment on the allegations because it’s an open case. County counsel has yet to file a response to the complaint.

Nationally, the number of inmate deaths has increased each of the past several years to a record high of 4,446 in 2013, according to the U.S. Bureau of Justice Statistics. Local jails in California reported 128 inmate deaths in 2013, up from 112 in 2012 and 92 in 2011. The leading cause of death in county jails is suicide.

The Sheriff’s Office and Department of Corrections (DOC), which jointly manage the county jails, have previously come under fire for suspicious in-custody deaths and excessive use of force.

In 1995, the county Board of Supervisors studied “Sudden In-Custody Death Syndrome,” unofficially called “Sudden Torture and Fatal Beating Syndrome,” after a mentally ill inmate's clash with guards left him in a coma. Civil rights groups raised the issue a decade later, calling for an independent investigation in 2004.

Historically, the DOC has cleared jail guards in the vast majority of excessive force cases. San Jose Inside has requested information about use-of-force complaints since 2011 to see if that pattern still holds true.

Officials from the Jail Observer Program, which provides independent but limited oversight of the county’s two jails, said most of its calls about officer roughness come from the Main Jail and many come from mentally ill inmates.

“Officer treatment of inmates is a recurring source of calls,” Kate Jones, a coordinator in the Office of Human Relations, wrote in the program’s 2014 annual review. “Reports of unnecessary rough handling and verbal insults occur regularly, although with caller acknowledgment that only some correctional officers are unnecessarily rough. Many of the reports come from inmates with mental health problems or in sections where security cameras are few or non-existent.”

While the Main Jail's eighth floor is designated for mental health services, it’s not enough to accommodate the population of inmates diagnosed with some type of mental illness. Outside of the eighth floor, hundreds more inmates are under heightened monitoring for mental health issues.

“These men and women are housed throughout the jail facility because [Custodial Health Services] lacks adequate dedicated housing for the real needs of their patients,” Jones wrote in her 2014 report. “This means they are held to the same behavior standards as healthy patients, which may explain some of the calls the [observer program] receives about rude and rough officer behavior.”

Over the past 15 years, the population of mentally ill inmates in California prisons has doubled, according to the DOC. A 2014 Stanford University study noted that 45 percent of California prisoners hd been treated for a severe mental illness within the past year. The National Sheriff's Association found that there are now twice as many mentally ill people in prison than in mental health treatment facilities.

Conservative estimates claim that about a fifth of Santa Clara County inmates suffer from mental health problems, though the rate is trending upward. But budget and staffing constraints make it difficult for already overcrowded jails to manage the influx of mentally ill inmates, who are more likely to act out.

"At current staff levels, it is impractical to send every officer through the special 40-hour training for working with mental health patients," Jones wrote, "despite the fact that every officer will encounter them."

This story has been updated.