It was his daughter-in-law, Susan Powell, who vanished. It was his son, Josh Powell, who was suspected of killing her and disposing of her body.

Yet Steve Powell was a central figure in a family ordeal that played out across two states and on national television. He was the only person to go to prison in the saga and was thought by Susan Powell’s parents to be the last, best chance to learn what happened to their daughter.

Those chances ended Monday when Steve Powell died at a hospital in Tacoma, Wash. Pierce County Sheriff’s Office spokesman Ed Troyer told news outlets in Washington the cause was a heart attack.

Steve Powell was believed to have been 68.

“I hope maybe he left some notes behind about where Susan might be,” Chuck Cox, Susan Powell’s father, said late Monday night in a short telephone interview. “And it’s a sad thing that his family’s destroyed, and now he’s gone, too.”

Word of Steve Powell’s death spread through friends and family of the still-missing Susan Powell, who learned about it from law enforcement in Pierce County, where Steve Powell again residedafter being paroled in 2017, hours before the public did.

Steve Powell was never convicted of any crimes having to do with Susan Powell’s 2009 disappearance, and he was already in jail awaiting trial when his son Josh Powell — Susan’s husband — murdered their two sons then killed himself in a fire in Graham, Wash.

Steve Powell was instead convicted of crimes related to photographing neighbor girls as young as 8 through their bathroom window. Yet, with the death of Josh Powell, the principal person of interest named in Susan’s disappearance, and the suicide of another son, Michael Powell, also suspected by some of participating in her disappearance, Steve Powell was considered by Susan Powell’s family as the last, most-likely person to know what happened to her.

Powell’s estranged daughter, Jennifer Graves, said she didn’t believe her father would have ever divulged anything he might have known about Susan’s disappearance, and she’s skeptical anything will be found in his personal effects.

“There’s a possibility, I guess," she said in a telephone interview. "But I don’t know if there will be anything there — if he’s learned his lesson and he’s gotten rid of anything that connects him with that.”

Susan Powell was last seen at her West Valley City home Dec. 6, 2009. Josh Powell has said he decided to take their sons, then 4-year-old Charlie and 2-year-old Braden, on a camping trip in the west desert despite a snowstorm that night. Josh Powell said he left his wife at home.

Steven Craig Powell was born in Portland, Ore. His mother split from her husband and moved her children to Coeur d’Alene, Idaho. He later joined The Church of Jesus Christ of Latter-day Saints and served a mission in Argentina.

He met Terrica “Terri” Martin at church in 1973. They began dating and married. The couple had a daughter, Jennifer, in 1974. She was followed by Josh in 1976. Sons John and Michael followed, and then another daughter, Alina. Steve Powell’s two daughters survive him, as does John Powell and the former Terri Martin.

Steve and Terri Powell filed for divorce in 1992. It was in the subsequent divorce and custody battle that many of the family’s problems were aired. Steve Powell left the LDS Church in the mid-1980s and became fiercely anti-Mormon — a stance that caused problems in his marriage and would later cause friction in his dealings with Josh, Susan and, after Susan Powell’s disappearance, the Cox family.

Terri Powell and her side of the family also claimed they had seen personality changes in Steve Powell. They described him as going from a friendly, fun man to one who was belligerent, condescending and speaking of government conspiracies and corruption. Terri Powell also told the court she worried about her ex-husband’s use of pornography and coarse language in front of their children.

Josh and Susan Powell met at a Mormon singles ward in Puyallup, Wash. The Powell family was still chaotic when the couple married in 2001. Steve Powell had a strained relationship with his eldest daughter and had strong influence over Josh and Alina Powell.

Susan Powell wrote in emails and journals that she felt uncomfortable around her father-in-law. Steve Powell worked in manufacturing and was an amateur musician who recorded his own songs on the keyboards. He wrote one about Susan Powell, furthering her discomfort. Josh and Susan Powell moved to Utah in 2004, in part, to lessen Steve Powell’s influence over them.

While armchair sleuths speculated Steve Powell might have had a role in his daughter-in-law’s disappearance, police found no evidence of that. In 2014, West Valley City police detective Ellis Maxwell, the lead investigator on the case, told The Salt Lake Tribune that Steve Powell was in Puyallup when Susan disappeared, and police found nothing proving he helped plan her murder or conceal it.

Josh and Steve Powell contended Susan ran away. In August 2011, Steve Powell went on television to read Susan’s journal entries showing she was emotionally unstable and capable of walking out on her family.

West Valley City police obtained a search warrant to seize those journals as evidence. During the search, they found the photographs of the neighbor girls. The authorities in Washington were notified, and Steve Powell was charged with counts of voyeurism and child pornography.

Josh Powell and his sons had moved in with Steve after Susan’s disappearance. Washington’s child welfare agency removed Charlie and Braden from the home and eventually placed them in the custody of their maternal grandparents. Josh Powell was allowed supervised visits.

On Feb. 5, 2012, Josh Powell opened the door of his rental house for his two sons, let them inside and closed and locked the door before the agent assigned to supervise the visit could get inside. Then Josh Powell hit his children with an ax, poured gasoline and ignited the house. FBI agents went to the jail to tell Steve Powell what had happened and ask whether he was ready to be more forthcoming about his daughter-in-law’s disappearance.

He wasn’t. Steve Powell went the rest of his years without deviating from his assertion that Susan Powell ran away or doing anything to find her.

While she said she believes her father had information about Susan Powell’s disappearance, Graves said she felt a sense of “relief” with his death.

“It’s the end of wondering if he’ll ever come around and, with a vengeful spirit, do something to me or my family Now, that’s not going to happen," said Graves, whose 2013 book, “A Light in Dark Places: A Story of Heartbreak, Survival and Redemption," chronicled the case. And she has long been clear about her belief that Steve Powell not only knew what happened to Susan but also directly influenced Josh to abuse his wife.

“My dad has done a lot of negative, even evil things. And he’s caused a great deal of pain and sorrow over many years," she said. "Long before Susan disappeared, he started creating pain for other people. And he’s had a big, negative influence on our family. Especially on Josh.

“But Josh still had choices. He could have always chosen not to take that path. He could have chosen not to listen to my dad.”

According to West Valley City police, the case remains assigned to a detective but “all leads ... have been exhausted and the case has gone cold.” The department released a statement that “Steve Powell’s death does not change the status of the Susan Powell disappearance case, nor does his death make the case any more or less likely to be solved."

Powell was convicted later in 2012 of voyeurism counts and served 30 months in prison. A jury had convicted him of two child pornography counts, too, but a judge dismissed those at sentencing, saying the contents of the photographs weren’t sexually explicit.

An appeals court later reversed that ruling. Powell, who was already out of prison, was arrested, tried and convicted of the child pornography counts again. In 2015, he was sentenced to another five years in prison. Between the credit for time served and time awarded for good behavior, Powell was paroled in July of last year.

Reporter Scott D. Pierce contributed to this story.