MANILA » A former U.S. Marine facing double murder charges in the Philippines has died of a heart attack in a northern city jail, police said Wednesday.

Timothy Kaufman, 37, was found unconscious and was declared dead on arrival at a hospital on Aug. 15, said Senior Police Officer Evelyn Pineda of Angeles City.

Kaufman was one of three men, including another American and a Filipino, accused in the murder of David Balmer, a former Irish police officer, and Balmer’s girlfriend, Elma de Guia, in September 2011.

The Filipino, Jesus Santos, has been arrested, while the other American, Joseph Tramontano, is at large.

Kaufman, from Knoxville, Tennessee, was arrested near his grandfather’s upstate New York home in April 2013 and was extradited to the Philippines in November 2014. He has denied involvement in the killings.

"I did not kill David and his wife," he said in a handwritten statement in January 2014. "The last thing I would have ever wanted was to be a public enemy in the Philippines."

Pineda, who investigated Kaufman’s death, said he had been under medication for hypertension and had filed a motion in court requesting hospital confinement, but the court hadn’t decided on it before he died.

Balmer, 54, and de Guia, 26, were found shot to death on their bed in a house owned by Richard Agnew, a club owner who had been a friend of Balmer’s since their days with Northern Ireland’s Royal Ulster Constabulary in the late 1970s. Agnew discovered the bodies and investigators recovered 18 spent 9 mm shells at the scene.

Kaufman was identified by security guards and by surveillance video as one of three men in a vehicle that entered the residential subdivision on the night of the killings. Tramontano, a former professional wrestler who managed a bar operated by Agnew, has fled the country.

Court papers filed in Kaufman’s extradition case allege that after the killings, he asked his maid to burn the contents of a garbage bag that included shoes and clothes worn by Kaufman and Tramontano. Kaufman also asked the maid to "bury something" and handed her two guns wrapped in a bath towel, the papers say.

The maid turned the guns over to police, who determined they were used in the killings. The recovered jeans had tiny blood splatters, according to Noly Bautista, an agent with the National Bureau of Investigation. Bautista has said the killings may have been drug-related, and that the two American suspects had been using cocaine and crystal methamphetamine.

Kaufman left the Philippines a month after the killings before he was identified as a suspect.

Associated Press writer Oliver Teves contributed to this report.