(CNN) -- The FBI will examine evidence and testimony from the trial of two California police officers acquitted this week in the beating death of a mentally ill homeless man to see whether his civil rights were violated, the agency said Tuesday.
The FBI began its civil right investigation shortly after Kelly Thomas, 27, died after a police beating in Fullerton, California, in July 2011. The violent confrontation drew national attention because a surveillance camera showed a wailing Thomas being beaten, clubbed and stunned with a police Taser. He died five days later.
"In 2011, the FBI opened an investigation to determine if Mr. Thomas' civil rights were violated during the altercation with Fullerton police officers," FBI spokeswoman Laura Eimiller said in a prepared statement. "With the conclusion of the state court trial, investigators will examine the evidence and testimony to determine if further investigation is warranted at the federal level."
On Monday, a jury in Santa Ana, California, acquitted former officer Manuel Ramos of second-degree murder and involuntary manslaughter and former officer Jay Cicinelli of involuntary manslaughter and excessive use of force.
The victim's father, Ron Thomas has filed a wrongful death suit against the city and the six police officers involved in the fatal incident. After the verdict, he said the jury's decision was "carte blanche for police officers everywhere to beat us, kill us, whatever they want."
In a CNN interview Tuesday, Thomas called his son's suffering "unfathomable" and said he was outraged that the officers will "get away with it completely."
"In a matter of minutes, he was dying in a pool of his own blood, and yet they're not guilty of even excessive force? That's unbelievable, unacceptable," Thomas said.
But John Barnett, the attorney for Ramos, said the officers "had no malice in their heart" and the video was "not the entire case."
"They did as they were told. They did as they were taught," he said. "When we send these guys out into the night not knowing if they're going to go home, we send them with instructions. When they follow those instructions and they do go home, they're not guilty of murder."
Thomas called that "garbage."
"They should have been responsible for their own actions as police officers," he said.
In closing arguments at the trial, Orange County District Attorney Tony Rackauckas told jurors that Ramos bore responsibility for Thomas' death because he threatened the uncooperative homeless man. Ramos can be seen on the surveillance video putting on gloves and shaking his fist in Thomas' face.
Thomas, a lifelong resident of Fullerton, was shirtless, carrying a backpack and wearing long pants and slippers when Fullerton police were called to investigate a "homeless" man looking into car windows and pulling door handles of parked cars at the city's bus depot on July 5, 2011, according to the father's lawsuit.
A security camera at the downtown bus depot provided 16 minutes of video of the officers questioning and then beating Thomas, who was schizophrenic.
Thomas' mother, Cathy, who's divorced from Thomas' father, received $1 million in 2012 from the city of Fullerton's insurance reserves in an agreement to settle her claim against the city in her son's death, city officials said. Cathy Thomas released the city and its police officers from all potential claims, officials said.
Ron Thomas said that since his son's death, police must have special training to work with the mentally ill -- a move he said could "correct all these things that could allow this to happen to Kelly."