The parents of American researcher Shane Todd, who was found hanged here last year, want a United States congressional investigation into his death.

"Our hope is that we get a congressional investigation because we fear that United States security has been compromised," said Mr Rick Todd in an interview near Buona Vista on Wednesday.

Mr Todd and his wife Mrs Mary Todd are in Singapore ahead of a coroner's inquiry from May 13 to 28 into their son's death. They believe their son was murdered because of his work for the Singapore Institute of Microelectronics, which they allege had links to a Chinese firm seen by the United States as a security threat.

Dr Todd was found dead last June in his apartment near Chinatown shortly after he quit the institute. He was 31.

"This story will not go away no matter how the judge rules in this inquiry," said Mrs Todd.

Since arriving in Singapore on Monday, the Todds have met with the team of five lawyers from three law firms here who will represent them during the inquiry. On Tuesday, they went through "two telephone books of testimony and pictures". Added Mr Todd: "We also had to bring our attorneys up to speed on things we had found out as well."

The Todds declined to comment on their plans for the inquiry but said that had brought several pieces of information for their lawyers, including a pathologist's report which suggested that Dr Todd had been murdered. They had also handed over to the Federal Bureau of Investigation a hard drive which they claimed contained work files belonging to their son.

"It's painful to go through this, but what we want is justice for Shane," said Mr Todd.