Christopher Watts apparently hoped to start a new life with his new girlfriend when he killed his wife Shannan Watts, along with daughters Bella and Celeste in August.
Shannan's dad Frank Rzucek called 33-year-old Watts -- dressed in an orange jumpsuit -- a "heartless monster."
"I trusted you to take care of them, not kill them," Rzucek said. "Prison is too good for you."
Judge Marcelo Kopcow, Colorado's 19th Judicial District Court, called the crime the most "inhumane and vicious" he's ever handled.
The evidence from the case was pieced together to tell the disturbing story, detailed by Weld County district attorney Michael Rourke, USA Today reports.
Watts had an emotional conversation with his wife, a Clifton native, on Aug. 13 before he strangled her to death then smothered both of his daughters, Rourke said.
Bella fought back, as indicated by cuts in her mouth and bite marks on her tongue, Rourke said, noting that Celeste had no defensive injuries, and Shannan had only one set of fingernail or finger print bruising on her neck.
A neighbor's doorbell camera shows Watts backing his truck in and out of his driveway three times to load the bodies. He buried the bodies in an oil field before placing three phone calls -- one to his daughters' school to disenroll them, one to a real estate agent to sell his house and another to his girlfriend to discuss their future, USA Today reports.
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