Shocking moment toddler walks in on mother's murder

A lawyer for the family of murdered Colorado mum Shannan Watts says the woman's toddler daughter walked in on father Chris Watts killing the woman.

Chris Watts strangled his wife and smothered his two young daughters, later pleading guilty to all three killings.

Attorney Steven Lambert - who represents Shannan's family - has shared disturbing details on Dr. Phil.

The pre-recorded interview is yet to air but has been seen by PEOPLE.

Lambert claims Bella, four, walked in on the murder.

"Bella walked in and asked, 'What are you doing to Mommy?'"

He says Watts told his daughter that "Mummy is sick", and needs to go to hospital to make her feel better.

The man later smothered Bella and sister Celeste, loading their bodies into his truck with their mother and hiding them at a oil work site where they were found three days later.

In November 2018, Watts pleaded guilty to all three killings and is currently serving five life sentences without the possibility of parole.

It was later discovered that Watts was having an affair with a co-worker at the time of the killings and it is thought his desire to start a new life was behind the despicable murders.

Lambert says Watts and Shannan were fighting about the affair when she was killed.

“In that fight, [Chris] essentially confessed to having an affair, that he wanted a divorce, that it was pretty much over between them,” Lambert told Dr.

“[Shanann] said something to the effect of, ‘Well, you’re not going to see the kids again.’ As a consequence of that conversation, he strangled her to death.”