State Police say they may never know what prompted an Oakland man to kill his girlfriend and two others before turning the gun on himself.

Public Safety Spokesman Steve McCausland released an update yesterday on the Oakland triple murder/suicide, saying the motive behind the triple murder/suicide remains a mystery. State Police say 42-year-old Herman Derico was a troubled man with mental health issues.

On November 4th, police found the bodies of 28-year-old Amy Derosby, her 30-year-old sister Amanda Bragg, and Bragg's 28-year-old boyfriend Michael Muzerolle inside a home on the Belgrade Road in Oakland. His body was found in the driveway with a self-inflicted gunshot wound. Because Derosby was Derico's girlfriend, her death is considered a domestic violence homicide.

An autopsy and toxicology tests completed by the State Medical Examiner's Office showed Derico had amphetamines, methamphetamine, marijuana, and alcohol in his system at the time of his death. Officials say there was also evidence of recent cocaine use. Detectives found that he had been treated at four hospitals in 2015 for mental health issues and had been prescribed drugs for anxiety, depression, sleep issues, and paranoia. Among the prescribed medications were citalopram, lorazepam, risperidone, and trazodone.

No suicide note was found that would have explained his actions. Police say it's likely the only people who could have explained his actions were killed by him that night.