Evidence has been presented in a Singapore investigation that a U.S. software engineer was unhappy at work and had written suicide notes before he died last year in what his parents insist was a murder.

The state counsel's opening statement said software engineer Shane Truman Todd was found hanging from a black strap secured to a door and had no visible signs of injury. Police found no signs of forced entry into the apartment, but they did find links to suicide websites on his laptop and suicide letters written to Todd's family members and loved ones.

Parents Rick and Mary Todd told The Associated Press in March they consider the evidence fake.

The inquiry that started Monday is expected to last 12 days.