Orange County prosecutors charged a Fullerton police officer with murder on Wednesday, saying he launched a lethal assault on a homeless man with the words: “My fists … are getting ready to f— you up.”

A second officer, accused of repeatedly smashing victim Kelly Thomas in the face with a Taser, was charged with involuntary manslaughter, District Attorney Tony Rackauckas announced.

It is one of the first times – if not the first time – that Orange County prosecutors have charged an on-duty police officer with murder.

Thomas, 37, a homeless man with a well-documented history of schizophrenia, died five days after his bloody encounter in July with police outside the Fullerton bus depot. A photograph of his face after the beating, disfigured with bruises, brought national attention to his death.

Officer Manuel Ramos, the first officer to confront Thomas, was charged with second-degree murder and involuntary manslaughter and was being held in lieu of $1 million bail. He appeared briefly in court on Wednesday, in handcuffs, and is scheduled to enter a plea on Monday. He faces a possible sentence of 15 years to life in prison.

Cpl. Jay Cicinelli, who prosecutors say joined the beating and shocked Thomas four times with a Taser, pleaded not guilty Wednesday to charges of involuntary manslaughter and excessive use of force under the color of authority. He was released on $25,000 bail. He faces a possible sentence of four years in prison if convicted.

Rackauckas said the officers delivered a barrage of blows to Thomas’ head and body as he cried out for his father and told them, “I’m sorry.” He said the beating began when Ramos confronted Thomas with fists raised and told him, “Now see my fists? They are getting ready to f— you up.”

Thomas answered: “Start punching, dude,” according to the District Attorney’s account.

“Ramos instilled in that victim fear, a reasonable fear for his life, that he was in danger and he was in danger by a police officer who wanted to F him up with his fists,” Rackauckas said.

Four other officers who were placed on administrative leave and under investigation after Thomas’ death will not face criminal charges. Rackauckas said his office’s investigation did not find criminal wrongdoing on their part. All six officers remain on administrative leave until the department decides whether to take administrative action against them, Fullerton police Sgt. Andrew Goodrich said.

Thomas died because of the force of the officers on his chest, which made it impossible to breathe, Rackauckas said in announcing the charges. Thomas fell unconscious, then slipped into a coma, and died when he was taken off life support five days later. The injuries to his face and head, Rackauckas said, contributed to his death.

Fullerton police have said officers were investigating a report of car burglaries when they stopped Thomas and tried to search him. In its account, the District Attorney’s Office said Thomas sat as ordered but didn’t follow Ramos’ command that he keep his hands on his knees. Ramos held up his fists, exchanged words with Thomas, and then grabbed his arm.

Thomas pulled away and ran. “Then the baton came out,” Rackauckas said.

Ramos, 37, is a 10-year veteran of the Fullerton Police Department. Cicinelli, 39, is a 12-year veteran in Fullerton. As a rookie officer in Los Angeles, he was shot during a traffic stop in 1996 and lost one of his eyes.

Ramos’ attorney, John Barnett, described the district attorney’s charges as “shocking” and said they would have a lingering effect on public safety in Orange County. “Officers will worry that their actions could lead to charges being filed against them,” he said. “He is being prosecuted for doing his job. It’s just wrong.”

Rackauckas opened his remarks by noting that “the public has been crying for justice for Kelly.” He said his office has been “in pursuit of the truth” since the week of Thomas’ death, an investigation that involved interviewing 151 witnesses and examining physical evidence, including batons and Tasers.

Kelly Thomas’ father, Ron, has demanded murder charges and has said at least some of the officers involved in the death of his son should face the death penalty. After Wednesday’s brief court hearing, he said Ramos “looks afraid now.”

“I feel they both looked today like cowards,” Thomas added. “They acted like cowards.”

Prosecutors will have to prove that Ramos displayed “implied malice” during the beating of Kelly Thomas in order to win a guilty verdict on second-degree murder. A jury will have to find that his actions were so inherently dangerous that death was a likely outcome.

Ramos was also charged with the lesser crime of involuntary manslaughter as a fall-back, in case the jury does not find him guilty of murder.

Legal experts say prosecutors often face a challenge in convincing a jury to convict a police officer. In part, that’s because defense attorneys often seek to cast what happened as a split-second decision made in the midst of a confusing and dangerous situation.

“Most jurors think it’s a tough job, it’s a job (they) wouldn’t want,” said Lawrence Rosenthal, a former federal prosecutor and a law professor at Chapman University. “(They think) if I made a mistake, I wouldn’t want to be charged as a criminal. And defense attorneys exploit that.”

At Fullerton’s City Hall, City Manager Joe Felz and three council members watched the district attorney’s news conference on live television with Michael Gennaco, an independent investigator hired by the city.

“We are delighted this has come forth,” Mayor F. Richard Jones said. “The DA has done an outstanding job of presenting this. … He was very succinct and clear. … It’s a tragedy for the officers, for the Thomas family and for the city.”

Councilwoman Sharon Quirk-Silva described the details in the district attorney’s presentation as “very emotional and disturbing.” She said she wants a citizens’ oversight committee to oversee the police department: “We definitely need a layer there, not only for the public but for the police.”

Gennaco, the outside expert hired by the city, is examining the Fullerton Police Department’s training, use-of-force policies and methods for dealing with homeless and mentally ill people. The FBI is also probing Thomas’ death.

“This has been a tragic event for Kelly Thomas, the Thomas family, the community, the police department and for all those who are involved,” Capt. Kevin Hamilton, Fullerton’s acting police chief, said in a prepared statement.

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