After his death, Todd's parents found that his hard drive contained a proposal between the Singapore outfit and a prominent Chinese telecom firm, Huawei, to build a powerful amplifier using gallium nitride technology.

The Todds showed the documents to CNN.

Huawei has been at the center of controversy.

It and another Chinese telecom company, ZTE, were cited last October by the U.S. House Intelligence Committee, which said the two firms "cannot be trusted to be free of foreign state influence and thus pose a security threat to the United States and to our systems."

That comment referred to the firms' business practices, and the committee report said, "the United States should view with suspicion the continued threat of the U.S. telecommunications market" by the Chinese companies.

Huawei rejected the committee report, calling the findings "baseless."

In reference to the proposal found on Todd's hard drive, Huawei and the Institute of Microelectronics in Singapore insisted they had no such project or even a business relationship, though they acknowledged preliminary talks.

Nothing became of those talks, they said.

"There is speculation by the Todd family that Shane's death was related to a project undertaken by IME with Huawei. Neither IME nor Shane was involved in any classified research project," IME said in a statement.

"The research and development carried out in IME is to advance economic growth for Singapore and deliver on healthcare and social benefits," it said.

IME isn't commenting further because Todd's death is under police investigation. "IME has cooperated fully with the authorities and will continue to do so," the institute said.

Huawei spokesman Scott Sykes said that gallium nitride, or GaN, technology improves power amplifier efficiency and is "widely recognized as a key technology for next-generation wireless base stations."

"IME approached Huawei on one occasion to cooperate with them in the GaN field, but we decided not to accept, and consequently do not have any cooperation with IME related to GaN," Sykes said in a statement to CNN.

The Singapore police have said they received "no response" from the Todd family to share evidence, including the hard drive.

"If they were not comfortable handing evidence in their possession to the Singapore Police Force (SPF), they could seek the FBI's help to review the evidence," a spokesman said. "As there has so far been no response to this request, SPF has sought the FBI's assistance to engage the family and for FBI to examine the evidence."

On February 20, Singapore police told the Financial Times that they had already examined the hard drive.

The couple, however, doubts that because the police description of the drive doesn't match the one they found in their son's apartment, they said.

The drive shows someone accessing it for only three minutes the night their son died and then again four days later, right before the parents visited his apartment for the first time, the parents said.

A forensic analysis of the drive shows someone reviewing, creating and deleting files during those two access events, the family said. That forensic analysis was conducted by a computer expert, the family said.

Singapore officials have invited the Todds to a coroner's inquest, scheduled to be held sometime this month. The parents aren't saying whether they would to return to Singapore.

Meanwhile, Max Baucus (D-Montana), chairman of the Senate Finance Committee, said his staff has met with U.S. Embassy and Singaporean officials in Singapore, and he has spoken with White House officials "to ensure this issue on their radar," a spokeswoman said.

Rick Todd had pictures taken of his son's body when it was returned to the United States.

The photos show bruises on Shane Todd's hands and a lump on his forehead, which the independent forensic pathologist said showed a fight, the parents said. The back of Shane Todd's neck was cut, the family said.

Shane Todd most likely was strangled by a wire, the pathologist told the family. Bruises also indicated that Shane Todd was trying to squeeze his hands under the wire, the family said. There was little fluid in his lungs; hanging typically takes several minutes making the lungs heavy with fluid, the pathologist told the parents.

"It's hard," Rick Todd said. "Every time I open those pictures, it's difficult.