(CBS) CENTENNIAL, Colo. - Isabella Guzman, a Colorado teenager accused of killing her mother late last month by stabbing her 79 times in the face, neck and torso, was formally charged with her murder Thursday, CBS Denver reports.
On Thursday morning, Guzman, 18, reportedly refused to leave her jail cell to appear in an Arapahoe County courtroom, forcing the hearing to be pushed into the afternoon. Guzman is accused of attacking her mother on Aug. 28.
Court documents state police found Guzman's mother, Yun Mi Hoy, stabbed to death in the upstairs of the family's home after responding to a 911 call.
Guzman allegedly ran from the scene and was captured by police the following afternoon.
The motive for the killing remains unclear. Friends of the victim say the relationship between Hoy and her daughter had been strained, but they don't know how it could have led to her death.
"I really don't know what made her snap. I really don't know why. It's just sad," Hoy's friend, Dana Daniel, told the station.
Robert Guzman, Isabella's father and Hoy's ex-husband, said he got a call from Hoy on the day of the murder indicating trouble between mother and daughter. He said things had been tense between the two women for some time.