The gun Clayborne Conley apparently used last week in a double-murder and suicide was a stolen weapon not registered to him, a police spokeswoman said yesterday.

No other details, including how Conley got the gun or what kind it was, were released as police continued to investigate the shooting deaths of a woman and her teenage daughter and Conley’s apparent suicide in the early morning a week ago today.

Kristine Cass, 46, and her 13-year-old daughter, Saundra, were killed in their Makiki Street cottage before Conley turned the gun on himself at about 1:30 a.m. last Friday, police said.

As many as half a dozen shots may have been fired, according to witness accounts.

Conley, a former Hawaii National Guardsman, and Cass had dated off and on, but she recently called off the relationship, according to friends.

Cass told a friend that she had decided to get a temporary restraining order against Conley after their relationship took a turn for the worse.

Because Conley had previously been acquitted of a crime on the grounds of mental illness, state law barred him from owning and registering a gun.

In a 40-year protective order issued against him in 2007 in a case involving another woman, a condition prohibited him from owning a firearm except for his military duties. He was discharged more than three years ago.

Conley had a history of violent behavior and mental instability. He and his unit were deployed to Iraq in 2004, and friends said he struggled with post-traumatic stress disorder.

Conley had several run-ins with the law, including misdemeanor charges for assault, terroristic threatening and violating a temporary restraining order.

Conley was committed to the Hawaii State Hospital in early 2009 and placed on conditional release seven months later.