A Colorado man told a judge he understood he has been charged with killing his pregnant wife and two young daughters and then hiding their bodies in an oil field as his father-in-law sobbed in the courtroom Tuesday.

Christopher Watts, wearing an orange jail suit and cuffed at the wrists and ankle, stoically answered, "Yes sir," as District Judge Marcelo Kopcow formally advised him of the murder charges and that he could face life in prison or the death penalty if convicted of killing his wife, Shanann, 34, and their daughters Celeste, 3, and Bella, 4.

Shanann's father, Frank Rzucek Sr., wept with his face in his hands. Shanann's brother, Frank Rzucek Jr., rubbed his father's shoulders and glared unflinchingly at Watts. A bailiff stood between them.

Watts didn't enter a plea to three first-degree murder charges, two counts of killing a child under 12, one count of unlawful termination of a pregnancy and three counts of tampering with a deceased human body.

Shanann's body was buried in a shallow grave in an oil field north of Denver and the girls' bodies were found submerged in nearby oil tanks, according to police arrest affidavit.

Watts told authorities his wife killed the children after he told her he wanted a separation. He said he erupted in rage after seeing her strangle one of the kids on a baby monitor and then strangled their mother inside the family's home, according to court documents.

Police first visited the home on Aug. 13, after a friend asked officers to check on Shanann. She had missed a doctor's appointment and wasn't answering calls or text messages hours after returning home from a business trip, the friend said.

Police searched the house and found Shanann's cellphone stuffed inside a couch. Her purse was in the kitchen and a suitcase was at the bottom of the stairs.

A detective spoke to Watts and learned about his plan to leave his wife. He said the conversation with Shanann was civil at first but that later "they were both upset and crying" and she planned to go to a friend's house, the court papers said.

When she and the girls did not return home Aug. 14, investigators ramped up their efforts with help from the FBI and Colorado Bureau of Investigation. Christopher Watts was interviewed by several local television stations, saying he missed his family and wanted them back.

It wasn't until last Wednesday night that he told investigators "he would tell the truth." Watts asked to speak with his father, then acknowledged killing his wife.

In court papers released Monday, investigators said they learned that Watts was "actively involved in an affair with a co-worker," something he denied in earlier conversations with police.

According to Watts' account, Aug. 13 began with an intense conversation. He said he told his wife that he wanted a separation, then walked downstairs.

When he returned, he said he spotted a baby monitor on his wife's nightstand and saw her "actively strangling" Celeste. He said it also showed their other daughter, Bella, "sprawled out on her bed and blue."

"Chris said he went into a rage and ultimately strangled Shanann to death," the document said.

Police found surveillance video from a neighbor showing Watts' truck backing into the driveway at 5:27 a.m. and then driving away from the house in Frederick, a small town on the grassy plains north of Denver where fast-growing subdivisions intermingle with drilling rigs and oil wells.

Watts, who worked as an operator for Anadarko Petroleum, said he loaded his wife and daughters' bodies into the backseat of his truck and drove to an oil work site about 40 miles (65 kilometers) east of the family's home. He buried Shanann's body and "dumped the girls inside" oil tanks, according to court documents.

Separate documents filed by Watts' defense attorney last week said the girls' bodies were submerged in crude oil for four days before police found them late Thursday. Their mother's body was found in a shallow grave nearby, prosecutors said.

The court filing says Watts gave police an aerial photograph and identified three areas where he placed the bodies. Investigators searched with a drone and spotted a bedsheet that matched other linens in the family home and fresh dirt.

Shanann's social media accounts are filled with photos and videos of the girls playing with their father and the couple smiling. They married in North Carolina nearly six years ago and moved to Colorado soon afterward.

District Attorney Michael Rourke said Monday that it was too early to discuss whether he will seek the death penalty. Watts will next be in court Nov. 16.