Dr. Shane Todd, 31, was found hanging in his apartment June 24, 2012, shortly after quitting his job at the Singapore Institute of Microelectronics, Straits Times reported.
In an opening statement at a coroner's inquest, Senior State Counsel Tai Wei Shyong added that 19 Citalopram pills, an antidepressant, were found in Todd's apartment.
Todd's girlfriend, Shirley Sarmiento, a neighbor, and two friends testified he had been stressed over work.
Sarmiento said Todd, an engineer, had told her he was working in a "dishonest environment" and that his boss had "stolen his team's ideas."
She added that Todd had once told her "heavy hands" were coming after him and that he was doing work that could get him into trouble with the U.S. government.
Todd's parents, who were present at the hearing, believe he was murdered, possibly over the transfer of technology from the institute to China.
The court was told a psychiatrist seen by Todd had prescribed him anti-depressant medication, Channel News Asia reported.
Tai, the senior counsel, said a search of Todd's computer revealed he had searched different methods of committing suicide, with the last occasion on the day before he died.