Seattle ? A Carnation, Wash., woman and her boyfriend armed themselves with handguns on Christmas Eve and walked over to her parents’ house, determined to kill them, according to police documents released in the slaying of six family members.

The daughter, Michele Kristen Anderson and her boyfriend, Joseph McEnroe, both 29, each shot Wayne Anderson in the head and McEnroe shot Judith Anderson twice, according to a police document released Thursday.

Then, when Michele Anderson’s brother and sister-in-law, Scott and Erica Anderson, and their two young children arrived shortly after, she and Joseph McEnroe shot the family of four to death as well, worried that they would otherwise be witnesses to the slayings of the Andersons’ parents, according to the police report.

The couple was denied bail by a judge Thursday and will remain in the King County Jail pending murder charges, which are expected today.

A probable-cause report from the King County sheriff’s department released Thursday spelled out how police believe the killings took place.

According to the documents, the suspects walked about 200 yards from the mobile home where they lived on her parents’ rural property, to the home of Wayne and Judy Anderson. Within 30 minutes of arriving, Anderson shot her father, 60, with a 9 mm handgun and then McEnroe shot him with a .357-caliber Magnum. McEnroe then shot Judith Anderson, 61, twice, police allege.

The suspects then dragged the bodies from the home to a backyard shed.

A short time later, Scott and Erica Anderson, both 32, arrived with their two children, ages 6 and 3. Police allege McEnroe shot the parents. He then shot both children in the head.

Police allege that Michele Anderson also shot her brother and his wife.

The couple were planning to escape to Canada when they were arrested Wednesday afternoon on suspicion of homicide after they showed up at the crime scene, a wooded property about three miles from Carnation.

A financial dispute might have led to the Christmas Eve slayings, according to a law enforcement source familiar with the investigation.

The possible motive emerged late Wednesday after the arrests. One law enforcement source familiar with the investigation said there was a dispute within the family over money and that Michele Anderson believed she had been mistreated and taken advantage of by relatives.