Benjamin and Kristi Strack often talked about the apocalypse and wanting to leave the evil they saw in the world, but friends and family thought that meant they would one day move somewhere remote and live off the grid.

Instead, they overdosed on a lethal combination of methadone, cold medicine and other drugs along with their three children, ages 11, 12 and 14, according to police.

There were troubling signs before the five bodies were found in a locked bedroom of their Springville home in September. The couple had struggled with drugs, as well as legal and financial problems. They also had been close friends with a Utah prison inmate serving a life sentence for killing family members in the name of God, slayings chronicled in the 2003 Jon Krakauer book "Under the Banner of Heaven."

Investigators determined the parents committed suicide, Springville Police Chief J. Scott Finlayson said at a news conference called Tuesday at the conclusion of the investigation. The younger two children's deaths were ruled homicides, although Finlayson said there were no signs of a struggle.

The manner of death for the 14-year-old, Benson Strack, was undetermined.

Police said Benson wrote a goodbye letter, leaving some of his belongings to his best friend. The only other recent writing the family left behind was a notebook containing handwritten to-do lists written as if the parents were preparing to go on a long vacation, like feeding the pets and finding someone to watch the house.

The five bodies were found Sept. 27 by Kristi Strack's older son from a previous marriage, along with the children's grandmother and a friend. The recording of the 911 call was released by police Tuesday.

"Oh my God," says friend Maureen Ledbetter, as grandmother Valerie Sudweeks is heard screaming in the background. "Is this 911? ... Oh my god. The whole family killed themselves."

During their investigation, police found years-old letters between Kristi Strack and Dan Lafferty, who is serving a life sentence after being convicted of committing a double-murder with his brother Ron.

"Under the Banner of Heaven" is about members of an offshoot of The Church of Jesus Christ of Latter-day Saints, told through the true story of the Laffertys' crimes. The two killed their brother's wife and 15-month old daughter.

Ron Lafferty is serving on Utah's death row for the July 1984 slayings of his sister-in-law, Brenda Lafferty, and her baby in American Fork. He claimed to have had a religious revelation sanctioning the slayings because of the victim's resistance to his beliefs in polygamy.

Investigators said Kristi Strack was obsessed with the case and struck up a friendship with Dan Lafferty.

"It was almost like he talked to her like one of his children," Lt. David Caron said. She and her husband both became close to him, and he had directed his remains to go to them after his death. They hadn't talked to him since 2008 and investigators do not believe the couple's beliefs came from Dan Lafferty, police Cpl. Greg Turnbow said.

"He felt really sad they had committed suicide," Caron said.

Benjamin Strack's brother Jacob said the final report from investigators wasn't surprising to relatives still mourning the family's deaths.

Looking back, the connection to Dan Lafferty was a worrying sign about the couple's mental state, he said.

The couple had a history of legal and financial problems and had gone through court-ordered drug treatment several years ago, according to court records, though investigators said they weren't aware of any contact with state child services workers. Benjamin Strack's boss, bricklaying company owner Alex Short, has said it appeared those troubles were behind them.

Benjamin Strack hadn't been to work for a week when their bodies were found with cups with a red liquid inside next to each of the bodies. The lethal drug mixture apparently came from a child's sand bucket found behind a door with traces of the same combination of methadone and cold medication that was found the children's systems.

Police believe Benjamin Strack died last, of a heroin overdose, because he was the only member of the family who wasn't underneath the bed covers. The methadone used in the deaths was prescribed to Kristi Strack, police said.

Springville is a city of about 30,000 near Provo, about 45 miles south of Salt Lake City.