"You evil monster": Chris Watts torn apart in court by the family of the wife he murdered.

Christopher Watts has been sentenced to life in prison for the murders of his pregnant wife and two young daughters at an emotional court hearing where he was also chastised by his wife Shanann’s family.

Watts’ father-in-law Frank Rzucek was the first to give his testimony at the sentencing for Watts, 33, who pled guilty to killing his 34-year-old pregnant wife Shanann and their two daughters, Bella, four and Celeste, three in August.

Denver7 shared videos of the hearing on Facebook.

“They were taken by a heartless one. This is the heartless one, the evil monster who dare take the lives of my daughter Shanann, Bella, Celeste and [their unborn son] Nico,” Rzucek said in court.

“I trusted you to take care of them, not kill them. They also trusted you.”

He said after their murders, Watts carried his family out of the house “like trash”.

Watts was arrested on August 15, just hours before police announced they’d discovered the bodies of Shanann, Bella and Celeste on a property owned by the Colorado man’s former employer. The girls had been submerged in crude oil vats, while their mother, who was 15 weeks pregnant, had been buried in a shallow grave nearby.

Rzucek repeatedly called Watts a “monster” and “heartless” throughout his statement.

“You have to live with this vision every day of your life and I hope you see that every time you close your eyes at night. You have no heart or feeling or love,” he continued.

At the end of his statement, Shanann’s father Frank Rzucek said he had a message for Watts, who sat silently behind him in an orange jumpsuit.

“Shanann says she’s super excited for justice today,” he said without turning to face his daughter’s killer.

Shanann’s brother echoed his father’s statement, saying that his family had looked up to and loved Watts, but now he wasn’t “even worth the time it takes for me to put this pen to this paper.”

Sandra Rzucek, Shanann’s mother wore a purple ribbon at the podium as she read out her statement: “We loved you like a son,” she said. “We trusted you. Your faithful wife trusted you. Your children adored you. And they also trusted you.”

For the first time, prosecutors confirmed to the hearing their understanding of Watts' motive for the murders and shared horrible details of how he killed his family.

Weld County District Attorney Michael Rourke said the killings were violent almost beyond comprehension.

Rourke said Shanann had been strangled, and Watts' daughters were smothered. His four-year-old daughter Bella showed signs of fighting for her life.

Authorities have said Watts was having an affair with a co-worker and believed his motive was so he could have a fresh start with this new love.

"The evidence tells us this: The defendant coldly and deliberately ended four lives, not in a fit of rage, not by way of accident, but in a calculated and sickening manner," Rourke told the court.

Watts refused to speak himself, but through his attorney said he was "very sorry".

Nearly two weeks after pleading guilty to their murders, as well as one count of unlawful termination of a pregnancy and three counts of tampering with a deceased human body, Watts was sentenced to life in prison without the possibility of parole.