Singapore is launching a public inquiry into the death of a US researcher whose family believes he was murdered because of a high-tech project for a Chinese firm that has been suspected of espionage.

More than 60 potential witnesses are due to take part in the coroner's inquest on Monday into the death of electronics engineer Shane Todd.

Todd was found hanged from a bathroom door in June 2012 in his Singapore apartment by his girlfriend, as he was preparing to return to the US.

Huawei Technologies, a Chinese telecom giant seen by Washington as a security threat, and Todd's former employer, Singapore's state-linked Institute of Microelectronics (IME), deny collaborating on any project involving Todd.

The scientist's parents, Rick and Mary Todd, are disputing a Singapore autopsy report that he committed suicide.

They say their son had feared for his life and left computer files linking his work at the IME to Huawei.

They have not accused anyone in particular of responsibility for his death.

"We believe our son was murdered. We know our son was murdered," said Mary Todd, 57, a church pastor.

She arrived in in Singapore last week with her husband, an airline pilot, to testify at the inquest.

Under Singapore law, a coroner's inquest is a fact-finding process to determine the cause of death in suspected suicides and other forms of "unnatural" death, with police findings forming part of the evidence.

In the run-up to the inquest, Singapore invited the Federal Bureau of Investigation to work with its police on the case after senior US officials backed the family's demands for a deeper probe.

Gallium nitride

The inquiry is scheduled to last until May 28, after which a verdict on the cause of death is expected in three to four weeks.

The case gained world attention when the London-based Financial Times reported in February that Todd, 31, was working on a project using gallium nitride (GaN), a semiconductor material that can be used in radar and satellite communications.

"Gallium nitride is used in active array radars, a new type of radar that requires powerful receivers and transmitters," a senior scientist told Al Jazeera in March, requesting anonymity because of the story's sensitivity.

The newspaper quoted Todd's mother as saying that the researcher - who had a history of depression - "felt he was being asked to compromise American security" at the IME in his dealings with "a Chinese company".

In reaction to the report, Huawei and the IME confirmed they discussed a potential project on GaN technology but said talks did not progress beyond preliminary stages.

'Cross-national conspiracy'

Singapore, a high-tech research hub which has close links with both China and the US, said there had been "no illegal transfers of technology" and welcomed a US audit of the IME's projects.

A US congressional committee last year labelled Huawei and ZTE, another Chinese telecom firm, as potential national security threats that should be excluded from government contracts and barred from acquiring US firms.

A Singapore lawyer not involved in the case said the inquest will focus on the cause of death.

"Questions of whether there is an element of cross-national conspiracy involved in the case will not necessarily be addressed in the inquiry. Those questions are not within the ambit of the coroner," said Sunil Sudheesan, of RHTLaw Taylor Wessing.

Earlier, Eric Watnik, a spokesman from the US embassy in Singapore, told Al Jazeera that while the Singapore authorities have requested FBI assistance for the investigation, it continues to be led by Singaporean police.

"The FBI continues to follow the case closely, but it does not have jurisdiction outside the United States and must be invited by a foreign government before doing any investigations overseas," Watnik said.