CASTLE ROCK, Colo. — A Colorado woman accused of killing her two young children faces four counts of first-degree murder because investigators have two theories about how the children died, a prosecutor said Friday.

Kelli Murphy, 41, also faces charges of fatal child abuse in the deaths of 6-year-old Madigan and 9-year-old Liam. She is being held without bail in the Douglas County jail in Castle Rock, about 20 miles south of Denver.

Deputy District Attorney Jay Williford refused to elaborate on the theories about the children's deaths.

Murphy called 911 Monday morning and said she was going to commit suicide and that her children were in heaven, authorities said.

Police said they found the children dead when they went to the Castle Rock home. The cause of death hasn't been disclosed.

Court documents show Murphy and her husband, Robert Eric Murphy, filed for bankruptcy in June and filed for divorce in February. Police said the couple had been living separately.

Kelli Murphy appeared in court Friday for a 15-minute hearing. She wore a black jail jumpsuit and flip-flop sandals. She appeared nervous and her feet jittered.

The judge ordered her to have no contact with her husband, but the reason for the order wasn't clear because she is incarcerated.

In March, a complaint of domestic abuse was filed and a judge issued a temporary restraining order involving the Murphys, but court documents did not say which spouse filed the complaint or who was named in the order. The restraining order was vacated a week later.

Court records show Kelli Murphy tried to withdraw her request for a divorce on April 26, saying she made it "wrongly, out of anger."

The court file in the murder case had been sealed, but a judge ordered some documents made public. A list of the files were expected to be available later Friday.

About 300 people gathered in a Castle Rock park Thursday night for a ceremony to remember the slain children.