The death of a 19-year-old found slumped in his cell a day after he was jailed on charges of running over and killing a police officer has been ruled a homicide, authorities said.

The Maryland Medical Examiner ruled Monday that Ronnie White's death in Prince George's County Correctional Center the previous day was from asphyxiation and strangulation.

Maryland State Police and the FBI are investigating the death. The FBI is focusing on possible civil rights violations.

Prince George's County Executive Jack Johnson said at a news conference Monday, "If we have vigilante justice, our society will fall apart."

Officials said seven guards had access to White at the time of his death, as did an unspecified number of supervisors. Authorities are also investigating whether anyone from the outside had access to the inmate.

The Associated Press has more details here.

(with wire reports)

This video is from The Associated Press, broadcast June 30, 2008.

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