Commenting on the ruling, Law and Foreign Minister K. Shanmugam said the theory that Shane Todd was murdered because he discovered illicit activity at the technology firm where he was employed was based on "untruths, pure fantasy and pure imagination."
Authorities had ruled Todd committed suicide in June 2012, but his family believed he was murdered because they found a hard drive in his apartment that contained sensitive documents from the Singapore Institute of Microelectronics, where he worked.
Shanmugam said an inquiry into the death was fair and open and "the world can see what we have done." Todd's parents should have the "strength to face the truth," he said.
Todd's parents said they plan to take the case up with U.S. President Barack Obama, the Straits Times reported.