ISLAMABAD, Jan 28 A security officer of the US embassy was found dead in his residence on Monday.

The embassy said no “foul play” was involved, but senior police officers thought otherwise.

They said it was too early to determine from the bullet wound in the skull of Mr Keith Ryan whether it was a case of suicide or homicide.

Keith Ryan, 37, was due to return to the US on Monday.

According to hospital and police sources, the embassy stopped the authorities from conducting post-mortem after the body was shifted to the Pakistan Institute of Medical Sciences.

Doctors there were allowed to carry out an external examination only. The embassy officials said an autopsy would be carried out in Germany.

The incident came to light when the embassy staff arrived at the house of Keith Ryan, on Street 63, Sector F-7/3, to take him to Islamabad airport for a US-bound flight.

As no response came from inside the house, the staff called police at around 9am. When they entered the house with the policemen, they found Mr Ryan lying in a pool of blood in the bathroom, a loaded pistol lying nearby.

The police and the embassy officials collected fingerprints and other evidence before shifting the body to Pims.

Sources at the hospital said Mr Ryan had a bullet wound in the back of his head. The bullet was still lodged in his skull, according to doctors.

Had he committed suicide by shooting himself through the mouth, the bullet would have exited, according to the doctors.

The medico-legal department of the hospital has asked the management to conduct an autopsy.

Mr Ryan, a senior official of the US Department of Homeland Security, was born in 1970. He was posted to Pakistan in Nov 2006. The department was set up after the Sept 11, 2001, attacks to keep an eye on immigrants.

Mr Ryan's designation was senior special agent.

He leaves behind his wife and three young children.

The Islamabad police, in a report to the federal government, ascribed the death to suicide, but said a final opinion would be given only after an investigation.