The police have asked the Federal Bureau of Investigation (FBI) to help in its probe into American researcher Shane Todd's contentious death.

Dr Todd, 32, was found hanged in his Singapore apartment in an apparent suicide last June. His parents, however, believe he was murdered over work he had done while employed at Singapore's Institute of Microelectronics (IME), which is part of the Agency for Science, Technology and Research.

A spokesman, responding to queries from The Sunday Times yesterday, confirmed that the police here have indeed approached the United States law enforcement agency for assistance.

Questions over the death of Dr Todd revolve around a hard drive that his parents said they had found at their son's apartment soon after his death.

They said the hard drive, which has fuelled their belief that their son was murdered, contains an IME plan to work with Huawei Technologies on a device that can improve satellite communications.

Although Huawei denies it, the US government has previously suspected the Chinese telecommunications giant of spying.

Despite earlier requests from the police here, Dr Todd's parents have refused to hand over the hard drive to the local authorities.

The police had said earlier that if the Todds were not comfortable handing over evidence in their possession, the FBI could help to review the evidence in the US. "As there has so far been no response to this request, the Singapore police has sought the FBI's assistance to engage the family and for the FBI to examine the evidence," the police said last night.

The US Embassy here confirmed yesterday that the investigation into Dr Todd's death "continues to be led by the Singapore police".

Separately, the Todd family reportedly met senior FBI officers in Washington DC on Friday. They also met a congressman, Mr Frank Wolf, and Senator Max Baucus, who has raised the case with the White House.