The 18-year-old Broomfield man accused in the slaying of a 13-year-old girl admitted to several friends that he killed her, according to evidence laid out in a preliminary hearing Wednesday in Boulder.Alexander Paul Pacheco is charged with first-degree murder in the October 2008 slaying of Kelsey Shannon. Her badly decomposed remains were found in a Broomfield drainage ditch last January.An autopsy determined that Kelsey died as a result of "homicidal violence."According to testimony in Pacheco's preliminary hearing, he told a friend he strangled Shannon "until her eyes rolled back in her head." He then stabbed her in the throat multiple times to make sure she was dead.Also revealed in court Wednesday: Pacheco admitted to a friend that he had sex with the corpse afterward until the body turned cold. He faces an additional charge of abuse of a corpse, based on that admission.A friend of Pacheco told police that Pacheco took him to the area where he had dumped the body and said he wanted to retrieve a condom that he used after killing Kelsey. The friend told police that Pacheco also showed a lock of hair he kept in a tissue that he said belonged to Kelsey.Pacheco visited the body several times in a watery marsh, according to police. Pacheco may have tried moving it with a sled to better hide it and also debated putting in a barrel filled with soda and bleach in the hopes it would eat away at the body. He said he could smash the teeth and spread them over Colorado so police couldn't identify the remains through dental records.Additional testimony revealed that Pacheco and Kelsey were a couple and that the two had sex during the relationship. On Oct. 14, Kelsey told her parents that she was going to go for a walk, after she and her parents had a disagreement about Kelsey's relationship with Pacheco. She never returned home and was reported as a runaway.Pacheco also told friends he wouldn't get caught because she had written a "runaway" note.The preliminary hearing is the first time evidence against Pacheco has been revealed. District Judge John E. Popovich will decide if there is enough evidence for Pacheco to stand trial.Pacheco has been held without bond since his arrest three days after Kelsey's body was discovered.