Since leaving prison last year, Mark Richard Geisenheyner, 51, had been vowing revenge on Paul Shay, one of the victims of a weekend shooting in rural Montgomery County, authorities said.
Geisenheyner broke into Shay's vacation home late Saturday and said, "Guess you never thought you'd see me again," before shooting Shay in the head, Montgomery County District Attorney Risa Ferman said Monday, citing a survivor's account.
He then shot four others, killing Shay's nephew and a toddler, authorities said. Shay, his wife and the toddler's mother remained in critical condition Monday.
Geisenheyner told friends that he had taken the rap and been cut out of the profits for an insurance scam he and Shay had concocted, Ferman said.
Geisenheyner was arrested for possessing artwork that had been reported stolen from Shay's home in 2006, and was sent back to prison on a parole violation, she said. Shay was not apparently charged, and Ferman did not know if there was any truth to Geisenheyner's account. Shay filed an insurance claim on the painting, which went missing about a month after a fire at his home.
"Fifteen months ago, when Geisenheyner got out of prison, he was determined to exact revenge on Paul Shay," Ferman said. He began casing the home three months ago, apparently unbeknownst to the family, she said.
The shootings Saturday in Douglass Township, about 30 miles northwest of Philadelphia, killed Shay's 43-year-old nephew Joseph Shay, of Yarmouth, Mass., and New York City, and 2-year-old Gregory Erdmann, of Fall River, Mass.
Paul Shay, 64, owns a plumbing company and lives in Manhattan's East Village with his 58-year-old wife, Monica Shay, who works as the director of the arts and cultural management program at Pratt Institute. They spent their free time at the Pennsylvania home.
Paul Shay and 37-year-old Kathryn Erdmann, the boy's mother and Joseph Shay's girlfriend, have been able to speak to investigators, officials said. They have extensive injuries but were expected to survive, authorities said.
On Sunday, hours after the rampage, Geisenheyner went to the home of a prison buddy and talked for several hours about the slayings, offering details not known to the public, officials said.
When he fell asleep, the friend and a companion sneaked out, calling police just before 5 a.m. Monday. Police and SWAT teams surrounded the home in Trainer, about 15 miles southwest of Philadelphia, and contacted the armed suspect by cellphone.
At about 11:30 a.m., police entered the home, found Geisenheyner in the basement and shot him. He had a gun with him, but it was not clear if it had been fired, Delaware County District Attorney G. Michael Green said.
"He was determined not to surrender, not to end up in a prison again," Green told The Associated Press. "He obviously indicated that he intended to seek revenge against the one victim. There's no explanation that I'm aware of as to why he would have shot at and killed multiple victims, including a 2-year-old child."
Geisenheyner had a lengthy criminal history dating to the 1970s, including robbery and burglary arrests, Ferman said.
He had a .45-caliber weapon with him Monday, but used a .22-caliber weapon in the Saturday shootings, the prosecutors said. Investigators found what they believe to be the murder weapon and other evidence Monday afternoon in a body of water not far from the Shay home.
Investigators had initially focused on possible ties to Joseph Shay because he had a recent criminal record, but the case took a quick turn when Geisenheyner's friend called police, Ferman said. His name had been on their radar already because of his 2006 arrest in the painting case.
John Penley, a freelance photographer in New York, said Paul Shay was known to help squatters and homeless people in the area.
"I thought his heart was in the right place when it came to the poor and the downtrodden," Penley said.
The plumber also was known for his business acumen.
"He definitely was worth a lot of money at this point in his life. He built that business up from a one-man operation to a major plumbing company," Penley said.
AP reporter Christian Salazar contributed to this report from New York.