Ghost Adventures stars Mark and Debby Constantino were found dead in their daughter's apartment in Sparks, Nevada, on Tuesday, ET has confirmed.

In what police believe to be a related incident, another unidentified man was found dead inside Debby's apartment. According to Reno police, 53-year-old Mark -- who was estranged from Debby -- is suspected in the deaths of both Debby and the unidentified man. He also took his own life.

Sparks police told ET that Debby was kidnapped from her apartment and was held hostage by her estranged husband. After negotiations failed with Mark, the SWAT team entered the home and found that both Mark and Debby were already dead. Police say they were able to locate Debby after her roommate found the unidentified man dead -- who was also their roommate -- and called the police to report Debby missing.

Mark and Debby have had multiple domestic incidents, according to Nevada's KTVN. In July, Mark was charged with kidnapping, domestic battery by strangulation and domestic battery against Debby, after which she obtained a restraining order from him. In a prior incident in March, Debby was also charged with domestic violence and battery with a deadly weapon against Mark.

The estranged couple starred in the Travel Channel reality show that follows ghost hunters as they investigate locations that are reported to be haunted.