Josephine Ruckinger had been estranged from family members for about 20 years.
She burst back into their lives briefly with deadly consequences.
Ruckinger and her husband, Jeffrey, both 43, broke into an Ashville, Pennsylvania, home, where they shot and killed her mother and brother, before being killed by Ruckinger's father, according to Pennsylvania State Police.
The woman's parents, John Sr. and Roberta Frew, had returned home from an evening out around 10 p.m. ET on Friday.
They were sitting in the living room with their adult son, John Jr., when their estranged daughter and her husband knocked at the door. When Roberta Frew answered, gunfire erupted, police said.
Investigators believe Roberta, 64, was shot by Ruckinger, while John Jr., 47, was shot in the left side of his chest by Ruckinger's husband.
Both Roberta and John Jr. died at the scene of apparent gunshot wounds.
Meanwhile, John Sr., 67, grabbed a .22-caliber revolver from a back bedroom. He allegedly saw his daughter point a gun a him.
He fired at least one round which, investigators believe, hit her in the head.
Ruckinger's husband then fired shots at John Sr., who responded in kind, Pennsylvania State Police said in a statement.
Once "the immediate threats had been incapacitated," John Sr. called 911 and waited, said police.
Ruckinger was pronounced dead at a nearby trauma center. By the time police arrived, her husband had died.
John Sr. was not injured.
Investigators do not believe John Sr. recognized that one of the two alleged attackers was his estranged daughter at the time of the incident.
A motive for killings is under investigation.
A search of the Ruckingers' car, parked at the bottom of the Frews' driveway, turned up a large amount of ammunition, a gas can, and a can of lighter fluid.
No charges have been filed against John Sr., police said.
"He was very cooperative with the investigation and his report of the events matches the physical evidence that we found," Pennsylvania State Trooper Matthew Evans said in an e-mail to CNN.
Ashville is a rural community located approximately 90 miles east of Pittsburgh.