Toxicology tests are needed to determine the exact cause of death. But, the assistant chief coroner says the 39-year-old may have died from a heart attack.
Monjack's publicist, Roger Neal, says he had been dealing with some health issues.
"As far as we know now, he passed away of natural causes," said Neal. "But he was due for a bypass surgery."
Monjack's death comes just five months after Murphy died of pneumonia. The coroner ruled prescription drugs contributed to her death.