The lawyer for the family of a homeless man who was allegedly beaten to death by six officers in Fullerton, California is seeking a federal investigation into the matter.

Kelly Thomas, 37, died five days after the July 5 beating. In video of the incident uploaded to YouTube last month, he can be heard screaming “Dad! Dad! Dad!” as police tased him.

The Fullerton Police Department has refused to release other surveillance video, but did allow the officers to see it before making their report.

“Let me tell that you we do believe first of all, that there is something sinister going on when the police chief decides to allow these officers to view the videotape before their reports are finalized,” attorney Garo Mardirossian told CNN’s Randi Kaye Tuesday. “When you have six criminals involved in a crime, you don’t put them all in one room and have them speak to one another, compare notes and watch a videotape to make sure that their notes jibe with the videotape.”

“We’ve already sent in notices on the state level of filing claims against the department, against these individual officers… The claims will include obviously the false arrest, beating to death of Kelly, and we’re going to have civil rights allegations involving the federal Constitution and the deprivation of Kelly’s right to live as a free citizen when he’s not bothering anyone. That will be prelude to a lawsuit later in both potentially state and federal courts.”

Watch this video from CNN’s Newsroom, broadcast Aug. 16, 2011.