Authorities have not discussed a motive
Jessica Bixler

Authorities in Indiana have confirmed that a 14-year-old boy fatally shot his cousin and her boyfriend last week before taking his own life.

A statement from the Greene County Sheriff's Department confirms Cole Bixler used 22-year-old George Mason's gun to kill him and 21-year-old Jessica Bixler.

The three bodies were found Friday.

Jessica was Cole's cousin, and had invited the teen to spend the previous night at her boyfriend's home, located just south of Owensburg.

Shortly before 5:30 p.m. on Friday, Jessica's mother called 911 after finding all three bodies inside the home, the statement says.

She told dispatchers the three appeared to be deceased from gunshot wounds.

Officers responded to the scene, and found Mason dead on the living room couch. The bodies of Jessica and Cole were found in her bedroom.

An autopsy determined single gunshot wounds to the head killed them all.

Police believe Mason was asleep at the time of his murder.

Want to keep up with the latest crime coverage? Sign up for PEOPLE's free True Crime newsletter for breaking crime news, ongoing trial coverage and details of intriguing unsolved cases.

"Bixler had mentioned to others he had been having thoughts of harming himself," reads the police statement.

A motive for the killings has not been disclosed.

No criminal charges will be filed connected to the case.