BOULDER, Colo. -- The Lafayette teen accused of conspiring to kill her mother and then leaving her body to rot in the family car has been charged with first-degree murder, the Boulder Daily Camera reported in its Tuesday editions.

Tess Damm, 15, now faces a possible life sentence in the slaying of Linda Damm, 52, as a result of the new charge.

The newspaper reported that the charged was filed last Wednesday but was not announced publicly and the new count was not added to the teen's court file until Monday. Damm is charged as an adult.

Damm now faces the same charge as her 17-year-old boyfriend, Bryan Grove, who was charged as an adult in early March with first-degree murder, the paper reported.

Damm and Grove are due in court Wednesday for a preliminary hearing, where prosecutors will present their case against them.

Police found Linda Damm's decaying body in the back of a Subaru in the garage of her Lafayette home on Feb. 28 after receiving an anonymous tip. The body had been left there for several weeks after Grove stabbed the woman to death in her bedroom, police said.

The home was recently sold.