Oct. 7, 2013— -- A central New York man, who is awaiting trial for the death of his son, is heard saying on never-before-heard tapes obtained by ABC News that he accidentally caused a truck to fall on his son, crushing him, and then left him to die.
Karl Karlsen, 52, is in a jail cell in Waterloo, N.Y., facing charges of second-degree murder and insurance fraud in the death of his son. Karlsen has pleaded not guilty.
In 2008, Karlsen's 23-year-old son Levi Karlsen was crushed to death when the truck he was working on slipped off its jack and landed on top of him.
While wearing a wire in a crowded restaurant last year, Cindy Karlsen, Karl's second and now estranged wife, asked her husband to tell the truth about his son's death. On the tapes, Karlsen said he had removed his truck's front tires and raised it on a single jack before Levi volunteered to do the repair.
The tapes, which had been played in court, had never been played publicly until now.
"I didn't push the truck, I said," Karlsen continued after Cindy pressed him for answers about Levi's death. "No, I said I had nothing to do -- but I said I took advantage of the situation once it happened."
With what police saw as incriminating statements captured on Cindy's audio recordings, they brought Karlsen in for questioning. During a nearly 10-hour interview, investigators said Karlsen denied killing his son 75 times, and that he's given several explanations for his son's death, including that he accidentally knocked the pickup truck off the jack and onto his son.
First, Karlsen is heard saying on police interrogation tapes obtained by ABC News that he had found his son's body earlier but didn't call police.
"I found him dead," Karlsen said. "I f---ing panicked. I don't know. I don't know."
When investigators asked Karlsen what he meant when he said he "panicked," Karlsen said, "I left him."
During the interrogation, Karlsen complained of feeling sick and needing pain medication, saying he has panic attacks. But finally he told police he had been there when the truck fell on his son.
"I opened the truck door because I had to get inside to move the linkage for the f---ing truck, and when I did, it tipped, and it just, whoosh, f---ing fell over," Karlsen said in the interrogation tapes.
But while he did admit he caused the truck to fall on his son during the police interrogation, investigators said Karlsen maintains it was an accident.
"He did admit that he caused the truck to fall on his son. He did admit that he left his son on the floor dying, but he never admitted that it was a planned, deliberate act," said Seneca County Lt. Investigator John Cleere.
Levi's death was initially ruled an accident in 2008. Police said Karlsen collected a $700,000 life insurance payout after the incident and that Levi had signed a handwritten will before his death, leaving everything to his father. But at the time, authorities said they didn't know about the life insurance policy or the will.
"The officers at the scene didn't see anything out of the ordinary," Cleere said. "They saw what appeared to be two grieving parents and what appeared to be an accident."
Police said Cindy Karlsen had her suspicions about Levi's death, especially after she said she learned that Karlsen had taken out a life insurance policy on her worth $1.2 million.
But Levi's death was not the first family tragedy in Karl Karlsen's life. His first wife Christina, who is also Levi's mother, died in a 1991 house fire, for which investigators said Karl Karlsen collected a $200,000 life insurance payout. At the time, Christina and Karl were living in Murphys, Calif., outside of San Francisco, with their three young children. Levi was just 5 years old at the time, and his two sisters were 4 and 7.
According to Christina's sister Collette Bousson, Christina and Karl were struggling financially and tensions rose in their relationship.
Karlsen told police that Christina was in a bathroom when some kerosene that had spilled suddenly erupted in flames. He got the kids out, but Christina was trapped in the fire. The window to the bathroom had been boarded up with 17 nails.
Karlsen told investigators the window pane had broken, so he had temporarily covered the window to keep out the cold and police ruled it an accidental fire. Christina's family had their suspicions, but Collette said, for the good of the children, they put their best face on things.
"I had to set aside all of my suspicions," she said. "I had to set aside everything that could have been a roadblock for me. Because I was absolutely going to make sure those kids knew their mother."
Karl moved across the country to New York State and got remarried, this time to Cindy. Even when Collette Bousson and her family heard that Karl's New York barn in Seneca County, N.Y., insured for $90,000, had burned down, she said they held their tongue.
But all that changed, Bousson said, the day she found out Levi was dead.
"I knew Karl did it," she said. "I didn't know what he had to gain. But I knew he did it."
Bousson said she tried to warn Cindy, but she wouldn't listen.
"We made it very clear that -- that she should probably be careful," she said. "Because we felt that she needed to know that there was a lot of suspicions around the fire in Murphys."
Thanks to a tip from an unnamed family member, New York and California authorities re-opened the investigations into both Levi and Christina's deaths. That's when Seneca County Lt. Investigator John Cleere got involved for the first time and started checking out the long string of what he said was suspicious incidents connected to Karlsen.
"It's extremely unlikely that someone would have that many tragic events a few weeks after they obtain exorbitantly high insurance policies," he said.
The connection might seem obvious to some, but legal analyst Jami Floyd said there are reasons why authorities might not have made the connection.
"Well, you would think insurance companies have every incentive not to pay out, but one insurance company doesn't necessarily communicate with the next company," Floyd said. "And when you take out a policy, especially if you have a nefarious intent, you might not go back to the same insurance company you used in the first place, 10, 15, 17, 22 years ago. You're going to go to a different insurance company."
According to the prosecution's theories, Karlsen killed his son and first wife for the insurance money.
Karlsen has pleaded not guilty to the second-degree murder charges for his son's death and denies any wrongdoing in Christina's death. The judge has ruled that the jury will be allowed to hear the recorded conversation he had with his wife, Cindy, and the videotaped interrogation.
Karlsen's lawyer Larry Kasperek, speaking on his client's behalf, said he respectfully disagrees with the court's recent decision to allow the jury to hear the recorded conversations his client had with his wife and the videotaped police interrogation.
Karlsen will go to trial for the murder of his son on Oct. 21.
The district attorney in California's Calaveras County told ABC News that her office is now actively investigating Christina's death as a homicide, and could not comment on an active investigation.
ABC News' Lauren Effron contributed to this story