Steven Lambert, an attorney for the family of the late Shanann Watts, revealed the information Tuesday during an exclusive interview on the "Dr. Phil" program.
Watts, 33, pleaded guilty to the crimes and was sentenced in November to life in prison without the possibility of parole. He was charged with three counts of first-degree murder in connection with the deaths of wife Shanann, and the couple's two daughters, Bella and Celeste.
Watts also received two additional concurrent life sentences for two other murder charges for different theories in Bella and Celeste's deaths. He also received 48 years for the unlawful termination of a pregnancy, and 12-year sentences for three counts of tampering with a deceased human body.
What are the details of the new alleged confession?
According to Thomas Grant — another lawyer for the family — 4-year-old Bella reportedly begged her father to spare her life moments before he smothered her.
Grant told Dr. Phil — Dr. Phillip C. McGraw, the show's host — that Watts decided to divulge the details of his family's death after finding God while serving a life sentence in prison.
"He is claiming that he is remorseful, and he has found God," Grant said.
Lawyers also said that contrary to popular belief, the couple's two daughters did not die in their home, but were killed after a 45-minute drive with their father and their mother's dead body.
Watts reportedly strangled his wife in their bedroom after a fight in which he purportedly admitted to having an affair. Watts told his wife that he wanted a divorce, to which Shanann reportedly responded that he wouldn't see his children anymore.
"In that fight he confessed to having an affair," Lambert told McGraw during the interview.
Bella reportedly entered the room as her father was wrapping his wife's dead body up in a sheet.
"[Bella asked], 'What are you doing with Mommy?'" Lambert recalled. "What [Watts] said was, 'Mommy is sick. And we need to take her to the hospital to make her better.' From our understanding, Bella did not witness the actual killing of her mother."
Watts then allegedly loaded his wife's body into the car along with his two daughters, who were still alive at the time. He then reportedly drove 45 minutes to his former work site where he disposed of his wife's body.
Lambert told McGraw that Watts disposed of Shanann's body while Bella and Celeste watched from the truck.
"He walks over, takes [Celeste's] favorite blanket, and smothers her," Lambert revealed. "Then, he takes her body, takes it out of the vehicle. At this point, Bella had unbuckled herself from the vehicle. He went back to the vehicle. Bella said, 'Please, Daddy, do not do to me what you just did to [Celeste]."
Lambert went on to detail Bella's death.
"There was a struggle from Bella. I believe there were signs that she fought for her life," Lambert explained. "Of the things that have been hard for [Shanann's family] to comprehend and to accept in this reality, what happened to Bella in those last moments has been the hardest."
Shanann's parents were in attendance during the interview.
What Chris Watts' Latest Confession Allegedly Reveals About Night He Killed Pregnant Wife And Two Children www.youtube.com
Police charged Watts with multiple felonies on Aug. 20 after Shanann — who was then 15 weeks pregnant — disappeared along with the couple's 3- and 4-year-old daughters from their home in Frederick, Colorado.
Three days after Shanann and the girls were reported missing, police discovered Shanann's body buried in the ground at a petroleum company where Watts worked. Authorities later discovered the remains of the couple's daughters, which were submerged in two nearby oil tanks.
Local police performed a welfare check on Shanann and her young daughters after the 34-year-old mom didn't show up for an afternoon doctor's appointment.
On Aug. 15, police arrested Watts and took him into custody.
In an unsealed court affidavit, police alleged that Watts was having an affair — a claim he initially denied. Watts admitted to killing his wife in a fit of rage, and said that his wife had strangled their daughters after he revealed he wanted a divorce.
You can read more about the case here.