Two US pathologists on Wednesday supported Singapore police findings that an American scientist found hanged last year in the city-state committed suicide and was not murdered as his family claims.
Medical examiners David Fowler of Maryland and Valerie Rao of Florida testified as independent experts a day after the family of the late researcher Shane Todd walked out of a coroner's inquest in Singapore.
Fowler rejected a theory put forward by the family's star witness, Missouri deputy medical examiner Edward Adelstein, who said Todd may have been killed by assassins working for two Asian high-tech firms involved in a secret project.
Fowler, chief medical examiner of Maryland, said marks on Todd's hands cited by Adelstein on Tuesday as proof of a fight with killers in his apartment were "the most classical example of post-mortem lividities" in hanging cases.
There was also nothing suspicious about a bruise on Todd's forehead, he said, declaring that "the cause of death was asphyxia due to hanging".
Rao, chief medical examiner of two districts in Jacksonville, also cited "asphyxia due to hanging" as the cause of death and agreed that there were no injury marks indicating a struggle.
Asked by a Singapore state counsel to give her opinion on the means of death, Rao replied: "Suicide".
Fowler and Rao based their findings on the Singapore autopsy report, while Adelstein relied on funeral pictures of the body and second-hand information.
Singapore police investigators earlier testified that the 31-year-old Todd, who had a history of depression, hanged himself in his apartment and left suicide notes to his family and friends on his laptop computer.
Foreign Minister K. Shanmugam, who is also the law minister, said the Todd family's decision to walk out was "regrettable".
"The police officers went on the stand, they were questioned, they gave their evidence, they gave their testimony. Their processes were subject to total scrutiny," he said.
In a statement Wednesday, the Todd family said it would "now turn to the court of public opinion with all the concrete evidence that our son was murdered".
But Todd's three bothers reappeared in court, saying they were there to show support for Ashraf Massoud, a computer analyst engaged by the family.
Massoud testified that any computer can be accessed remotely and its contents, including the Internet history, altered.
Police experts had testified that Todd repeatedly searched suicide and depression websites before his death.
A coroner's inquest is a routine procedure for suspected suicides in Singapore. But the case has taken on a high profile because of the conspiracy theory and strong political lobbying by the Todds in Washington.
Shane Todd's former employer, Singapore's state-linked Institute of Microelectronics (IME), and China's Huawei Technologies have denied claims by the family that they were working on a secret project involving Todd that could compromise US security.
But they confirmed holding preliminary talks on a potential research venture. Todd was part of an IME research team working on gallium nitride, a semiconductor that can be used in radar and satellite communications.
Witnesses have described Todd as under severe stress in the weeks before his girlfriend found his body on June 24, 2012.
His former IME colleague, French scientist Joseph Romen Cubillo, testified Wednesday that Todd had become secretive in the weeks before his death.
Cubillo said the IME was involved in "defence-related projects that are not classified" but he did not know if Todd was involved in such work.
"I do not think or believe that Huawei is involved in Shane's passing," Cubillo said.
A US congressional committee last year labelled Huawei and ZTE, another Chinese telecom firm, as potential security threats that should be excluded from US government contracts and barred from acquiring US firms.