Demonstrators hold a moment of silence at a makeshift memorial for Kelly Thomas, a homeless man who died after an altercation with several officers, during a rally and protest march on August 20, 2011 in Fullerton, California.

Story highlights

Joseph Wolfe, 37, was charged with involuntary manslaughter of a homeless man

He is accused of participating in the killing of 37-year-old Kelly Thomas

Thomas, who was mentally ill, was beaten to death in July 2011, officials say

Wolfe is the third former officer to be charged in the case

Los Angeles CNN  — 

A third former Fullerton, California, police officer was charged in the beating death of a mentally ill homeless man, the Orange County district attorney said.

Joseph Wolfe, 37, pleaded innocent Thursday to one count of involuntary manslaughter and one count of use of excessive force in connection with the death of 37-year-old Kelly James Thomas on July 7, 2011.

The charges against Wolfe came as a result of a grand jury indictment handed down on Monday, District Attorney Tony Rackauckas said in a statement.

Since Thomas’ death, the district attorney’s office “has actively continued its investigation and legal review and decided to seek indictment against Wolfe following extensive legal and factual analysis and development of evidence,” the statement said.

California cop pleads not guilty in homeless man’s death

Wolfe was released on $25,000 bail, according to authorities at the Orange County jail. He faces up to a maximum four years in prison, if convicted.

Wolfe’s defense attorney, Vicki Podberesky, did not immediately respond early Friday to a CNN request for comment.

The indictment against Wolfe comes nearly a year after two other former Fullerton police officers were charged in the case. They were ordered to stand trial in May.

The grand jury heard testimony from 10 witnesses and reviewed 113 exhibits of evidence over three days before handing down the indictment against Wolfe, the statement said. State law requires grand jury transcripts to be sealed for 10 days after the defense has received the documents.

Thomas, a lifelong resident of Fullerton, was shirtless and carrying a backpack, and was wearing long pants and slippers, when Fullerton police were called to investigate a “homeless” man looking in car windows and pulling door handles of parked cars at the city’s bus depot last July, according to a lawsuit filed by Thomas’ father.

Father sues California police

A security camera at the downtown bus depot provided 16 minutes of video of the officers questioning and then beating Thomas, who was schizophrenic.

Former Officer Manuel Ramos is charged with second-degree murder and involuntary manslaughter, and former Cpl. Jay Patrick Cicinelli is charged with involuntary manslaughter and felony use of excessive force.

Both have pleaded not guilty. A pre-trial hearing is scheduled for November 30.

Ramos, 37, a 10-year veteran of the police department, faces a maximum sentence of 15 years to life, if convicted, authorities have said. Cicinelli, 39, a 12-year Fullerton police veteran, faces a maximum of four years in prison, if convicted.

Recently, Thomas’ mother, Cathy, received $1 million from Fullerton’s insurance reserves in an agreement to settle her claim against the city in her son’s death, according to a city statement. Cathy Thomas, who’s divorced from Frederick “Ron” Thomas, released the city and its police officers from all potential claims, the city’s statement said.

Thomas’ father, Frederick Thomas Jr., filed a lawsuit in July against the city, its police chief and the six officers allegedly involved in the fatal incident. The lawsuit seeks more than $25,000 in damages.

Homeless man cries ‘help me’ as cops fatally beat him in videotaped incident

CNN’s Chelsea J. Carter contributed to this report.