Singapore (CNN) -- A police investigation into one man's death has now become an issue between two countries.
Singapore's Foreign Ministry on Sunday said it was "deeply disappointed" by the attempt of two U.S. senators to block funding to the country's state-backed Institute of Microelectronics in a dispute over the investigation into the death of American who had worked there.
U.S. Sens. Max Baucus and Jon Tester of Montana recently introduced a measure to block U.S. funding to the institute until U.S. Attorney General Eric Holder certifies that the FBI had full access to all evidence related to the death of research engineer Shane Todd.
Todd's parents, who are from Montana, had raised the issue with the senators in early March. Baucus told reporters in Washington that he will work until he is "satisfied that the parents have closure, and I am convinced there has been no national security breach or improper transfer of technology that puts America at risk."
According to a statement from the senators, in 2010, IME received nearly $500,000 from the Defense Advanced Research Projects Agency, part of the U.S. Department of Defense responsible for the development of new technologies for use by the military.
It was unclear what proportion of IME's overall budget the U.S. funds amounted to.
Parents call death suspicious
Todd was found hanged in his apartment in June, just days after resigning from a job at IME. His death was reportedly called a suicide in initial reports by a Singapore coroner. A further investigation is under way in Singapore before a final coroner's report.
Todd's parents consider their son's death suspicious and think he could have been killed because of his work on a semiconductor project between IME and the Chinese telecommunications giant Huawei.
The Singapore police last week issued a statement asserting that they were cooperating with the FBI and said they also told the FBI they will share evidence obtained so far "in accordance with the legal framework of both countries."
The senators' latest move came despite a meeting between Baucus and Singapore's Foreign Minister K Shanmugam on Tuesday.
Shanmugam has said IME is subject to "rigorous internal audits" and offered to allow the United States to conduct its own "process audit" of IME as well.
Hard drive holds evidence?
Singapore police have also sought help from the FBI to obtain a hard drive that had been in Shane Todd's apartment and may contain relevant evidence.
His parents say they found the drive in their son's apartment after police had already conducted their search.
They also have said that experts who've examined the drive say someone accessed the drive after Todd's death.
The parents have told CNN they are holding the drive "at an undisclosed location."
Both IME and Huawei have denied any joint projects related to Todd's work were being conducted.
Huawei is one of the world's largest telecommunications equipment makers.
Along with its Chinese rival ZTE, it has been seeking to expand its business in Western markets.
But at times, the two companies have met with resistance over security concerns and fears over their ties to the Chinese government.
In October, a report prepared by the U.S. House Intelligence Committee said that "the risks associated with Huawei's and ZTE's provision of equipment to U.S. critical infrastructure could undermine core U.S. national-security interests."
The two Chinese firms disputed the reports' findings, saying their products were safe for use in the United States.
Todd's parents say his work had involved the use of an advanced semiconductor material Gallium Nitride, which has both commercial and military applications.
They say he had expressed concerns about the legality of his work and whether it could be harmful to U.S. security.
Singapore denies there were any illegal transfers of technology between IME and Huawei.
In a statement from Singapore's Foreign Ministry, Singapore also objected to the "pressure" in this case and said the country has "made every effort to be open and transparent in both the investigation of Mr. Todd's death and the IME's projects."
"We will let the outcome of the investigation and coroner's inquiry speak for themselves."