Maryland ? A man arrested in the hit-and-run death of a police officer was found strangled in his cell, and investigators focused Tuesday on guards at the suburban Maryland jail, which has a history of security lapses.

As state police took over the investigation, an attorney for inmate Ronnie L. White’s family said the young man’s attackers “took it upon themselves to be both the judge, the jury and the executioner.”

White’s death shocked and angered officials in Prince George’s County, including County Executive Jack Johnson, who likened it to “vigilante justice.”

Investigators from the FBI and state police joined the case Monday after the state medical examiner concluded that White had been strangled Sunday morning.

White, 19, was arrested early Saturday on charges of ramming a stolen pickup truck into police Cpl. Richard Findley. Findley had gotten out of his police cruiser Friday while trying to conduct a traffic stop on the truck. White allegedly struck him and dragged him for a short distance in the community of Laurel.