Olivia Newton-John was said to be haunted for the rest of her life by the mysterious disappearance of her ex, who vanished during a 2005 fishing trip off the California coast.

The decades-long disappearance of cameraman Patrick McDermott is being revisited in Matthew Hild’s new biography of the Grammy-winning superstar, “A Little More Love.” The book explores the lasting toll the unsolved case took on the singer, beloved by generations as Sandy in the blockbuster musical “Grease.” Newton-John died in 2022 at age 73 after a long battle with breast cancer.

“It’s still an unsolved mystery,” Hild told Fox News Digital. “Olivia said at one point that this would haunt her forever because nobody would ever really know what happened. And to this day, there are reports that Patrick McDermott is believed to be alive in Mexico.

“But what she finally told one of her closest friends was, ‘I don’t believe that. I believe he was killed. I think he drowned.’ And I don’t think she ever really made peace with it, because how do you make peace with something like that?”

On June 30, 2005, McDermott boarded the fishing vessel Freedom and embarked on an overnight fishing trip while Newton-John was in Melbourne. The 48-year-old’s family grew worried after he failed to attend an event with loved ones. McDermott’s ex-wife also revealed that he hadn’t picked up their 13-year-old son as scheduled.

After contacting authorities, McDermott’s family learned that he had left a bag full of belongings on the boat, and his car was still parked in the lot at San Pedro’s 22nd Street Marina.

According to the book, Frank Liversedge, the marina’s landing manager, said that he believed McDermott “did not disappear at sea and probably made it to shore, but left his possessions for unknown reasons.” He added, “I’ve been here 45 years as a boat captain and vessel master. I have never lost a fisherman.”

Hild said that as tabloids swarmed a devastated Newton-John, it wasn’t publicly revealed that she and McDermott were in an on-again, off-again relationship. While they were “off-again” at the time of his disappearance, they hadn’t formally ended their relationship.

“Some of the people I interviewed confirmed this,” Hild said. “They also remember that at the time he disappeared, Olivia and Patrick had taken a break from each other, but that didn’t necessarily mean a final breakup, because they’d done that before. At the very least, he was a close friend of hers, regardless of the state of their romantic relationship. So obviously it was a huge blow to her. And I think this was another example of her strength and resilience.”

Persistent reports suggested that McDermott had been depressed and heavily in debt. According to multiple reports, McDermott filed for bankruptcy in 2000 and still owed child support payments. Still, friends said McDermott showed no signs of depression and was a doting father who would never abandon his son.

Hild said there were growing rumors of McDermott faking his own death, with some insisting they spotted him in Mexico. Newton-John, desperate for answers, tried to take matters into her own hands.

Speculation surrounding Mexico emerged after several reported sightings of McDermott there in the years following his disappearance. Tabloids and private investigators claimed he had been living under an assumed identity in coastal Mexican towns, fueling conspiracy theories that he faked his own death to escape financial troubles. However, no conclusive evidence ever surfaced to confirm those claims.

“She hired Gavin de Becker, who was her longtime personal security expert,” Hild said. “Gavin de Becker is still a security expert to the stars and has worked with her for years. She hired him to send his team down there and try to find Patrick McDermott. They never found him, never found any tangible evidence that he was still alive.”

In August 2005, Newton-John issued a public statement: “I am hopeful that my treasured friend is safe and well, and I am grateful to the officials who are working so hard to find Patrick, whom I love very much. I ask anybody with information that could help to please, please come forward.”

Hild said Newton-John never bought into the rumors and conspiracy theories surrounding what happened to McDermott, but questions about his fate followed her for years.

“It’s a really painful topic,” she said on “Showbiz Tonight” in October of that year, as quoted in the book. “And it’s still under investigation. And I’m just — I love him very much, and as you can imagine, this is an incredibly hard thing to go through.”

“I was just kind of frozen,” she shared. “And you know, life, you have to move forward a little bit. It was one of the reasons that I decided to sing again. I didn’t think I was going to sing again, and I had to move forward.”

Dance instructor Joe Giamalva told Hild that in the months after McDermott vanished, Newton-John immersed herself in tap dancing classes at Malibu Fitness. “I think it was a getaway for her,” he said. “It was an hour she could get away and take her mind off all that s–t.”

Hild wrote that a year after the “Showbiz Tonight” interview, Larry King surprised Newton-John by bringing up McDermott’s disappearance. Newton-John told him she remained in contact with his family.

“I’ve become very close to his ex-wife, Yvette [Nipar], who’s a wonderful person, and we’ve become good friends, and I see his son, and he’s thriving. He’s doing really well,” she told King.

That’s when King publicly mentioned McDermott’s son, Hild said.

Nipar later said, “I’ll never forget her calling me from the green room right after this, knowing how protective I was about my son’s name constantly being put out there. She had no idea Larry was going to ask this.”

Hild said that over the years, Newton-John became protective of Nipar and her son.

“This was a personal tragedy for Olivia,” Hild said. “She became close friends with Patrick’s ex-wife and Patrick’s child as well. One of Olivia’s biggest concerns was that every time she was asked publicly about Patrick’s disappearance and the conspiracy theories surrounding it, the attention would affect Patrick’s child and his ex-wife.”

In 2009, the U.S. Coast Guard issued a statement saying the agency was “not actively investigating this case,” People magazine reported.

“The Coast Guard Investigative Service closed its case Sept. 15, 2006, and did not find any evidence of criminal action, suicide, accident or hoax in the disappearance of McDermott,” the Coast Guard said in its release.

“A separate marine safety investigation followed, looking into the operation of the fishing vessel itself and was closed Oct. 30, 2008. A marine safety investigation is standard in cases of loss of life in the marine environment.”

“Both investigations suggest that McDermott was lost at sea,” the statement concluded.

That same year, Newton-John told a journalist, “I think there will always be a question mark. I don’t think I will ever really be at peace with it.”

Hild said the case continued to trouble Newton-John.

“It was a heavy personal burden,” he said. “Just the disappearance alone, but also the nonstop press scrutiny, all the way through her death and even beyond. This question won’t go away.”

Newton-John began dating McDermott shortly after her 1995 divorce from Matt Lattanzi. They were together, on and off, for about nine years.

“I talked to some people who knew Patrick pretty well,” Hild said. “Aside from being a photographer and a cameraman, Patrick was a guitar player. And so, the guys in Olivia’s band would jam with him. They all said he was a kind, sweet person. I didn’t hear anybody who said a bad word about him. I talked to probably a dozen people who knew him and, across the board, they all said he was a very kind person.”