A Holtsville man claims a Suffolk cop assaulted him at his home, and caught the moments just before the attack on tape.

James Masten alleges Suffolk County Police Officer Keith Murphy came to his house on July 4, forced him inside and roughed him up.

"He is pulling up and saying 'Get off the phone right now and get in the house,'" Masten said while showing the video exclusively to News 12 Long Island. "He grabbed me and 30 or 40 times threw me up against the wall."

The physical altercation in the alleged assault was not videotaped.

Masten said his estranged wife, Elicia, a civilian employee in the 6th Precinct, disappeared June 30 with their 4-year-old daughter. Elicia was in Murphy's front seat during the incident, Masten claims.

"Clearly [Officer Murphy] was acting on behalf of a personal relationship with Mr. Masten's wife," Ronald Levinson, Masten's attorney, said. "This is not something he was responding to under his active duty."

Suffolk police confirm there is no radio record of Murphy being dispatched to Masten's house. According to police, Masten filed a complaint on July 4 and an internal affairs investigation has been opened. Levinson said he and Masten plan to file a lawsuit against the Suffolk County Police Department Thursday.