Fox News Digital spoke with John and Callahan Walsh about the upcoming season three of 'America's Most Wanted' on FOX.
If you or someone you know is having thoughts of suicide, please contact the National Suicide Prevention Lifeline at 1-800-273-TALK (8255).
When Nathan Carman, a Vermont man accused of killing his mother at sea over an inheritance, died by suicide, many believed he took his secrets to the grave.
But one true crime author believes that if the 29-year-old hadn't killed himself in his jail cell, there wouldn't have been enough evidence to convict him.
He argued that there were other suspects that could have been looked at, ones that Carman likely didn't realize were present.
NATHAN CARMAN, VERMONT MAN ACCUSED OF KILLING MOTHER AT SEA, DIES AWAITING TRIAL
Nathan Carman died in 2023 in jail while awaiting trial, federal authorities said. (Suzanne Kreiter/The Boston Globe via Getty Images)
"I do not think there was going to be enough evidence to convict him," Casey Sherman told Fox News Digital. "This was a no body case. Everything was circumstantial when it came to his mother's disappearance.
"... I told investigators, 'Let's follow the theory that Nathan murdered his mother. How would Nathan plan his getaway? They never answered that question for me. I don't think they could've answered that question themselves."
Sherman has written a new book, "Blood in the Water," which delves into Carman's brief life and his theories about what took place. For the book, he spoke to Carman's loved ones, investigators, and others closely connected to the case. Sherman's 2006 bestseller, "The Finest Hours," became a 2016 film.
FOLLOW THE FOX TRUE CRIME TEAM ON X
Casey Sherman's book, "Blood in the Water: The Untold Story of a Family Tragedy," is available now. (Sourcebooks)
Sherman said that Carman appeared determined to prove his innocence during his final months. In 2022, he pleaded not guilty to fraud and first-degree murder in the death of his mother, Linda Carman. He was scheduled to go on trial the year he died.
Nathan Carman departs federal court on Aug. 21, 2019. He was scheduled to go on trial in October 2023. (AP Photo/Steven Senne)
Carman was the sole occupant of a county jail cell in New Hampshire where guards found him dead. One of his lawyers, Martin Minnella, said Carman appeared "in good spirits." They last spoke on the day before he died, and they had planned to meet with experts about his case.
"I would describe his final months as being very active in his defense," Sherman explained. "His death came as a shock to everybody, including his attorneys. Nathan had a very strong defense against the disappearance and potential murder of his mother... He was looking forward to his day in court, and he never got it."
A US Coast Guard boat brings Nathan Carman to a Coast Guard base in Boston on Sept. 27, 2016, after surviving the sinking of his 32-foot fishing boat near Block Canyon, off New York, in the Atlantic Ocean on Sept. 18. (Suzanne Kreiter/The Boston Globe via Getty Images)
"The circumstances surrounding his death in jail are certainly mysterious to me and others," Sherman shared.
SIGN UP TO GET THE TRUE CRIME NEWSLETTER
While true crime author Casey Sherman found the circumstances surrounding Nathan Carman's death "mysterious," the attorney general's office confirmed that authorities didn't consider his death to be suspicious. (AP Photo/Elise Amendola