Christopher Watts: A man escapes the death sentence by admitting the murder of a woman and her pregnant daughters

A father confessed to murdering his pregnant wife and two young girls before throwing their bodies into an oil field.

Christopher Watts, 33, has agreed to a plea agreement to avoid the death penalty for killing Shanann Watts, 34, and the couple's two children, Bella, four, and Celeste, three,

He had first told the police that he had strangled his wife after killing them at their family home in Colorado, a complaint that prosecutors have dubbed "unfounded lie".

Watts' voice trembled when he pleaded guilty to three counts of first degree murder in the Weld County Court.

He also admitted two counts of murder of a child under the age of 12, harm to the body of the three victims and illegal termination of a pregnancy.

Shannann Watts was 15 weeks pregnant when her husband killed her at home in Frederick, about 30 km north of Denver, on August 4.

He then loaded the bodies of his wife and daughters into a truck and drove them to an oil company where he worked.

There, he immersed their remains in crude oil.

After reporting the disappearance of his family, Watts appeared on television several times to demand their safe return. He was arrested on August 15 and their bodies were found a week later.

Watts told detectives that his wife had killed their daughters after an argument after he told her that he wanted to divorce her.

"The projector he's been trying to steal on Shanann – falsely, falsely and frankly an absolute lie – has been corrected," said Weld District Attorney Michael Rourke after Watts acknowledged his responsibility.

Under Colorado law, a conviction for first degree murder is punishable by life imprisonment without the possibility of parole.

"He deserves a life sentence for every act," Rourke said.

Watts had faced the possibility of the death penalty if he was found guilty at a trial, but under the plea agreement, prosecutors pledged not to seek the trouble.

Mr. Rourke said he went to North Carolina, where Shanann Watts' family lives, to consult them before concluding the agreement.

Prosecutors did not say what they thought motivated Watts to murder his wife and children.

He had an affair with a colleague and the family had considerable debts.