Officials in West Texas plan to reveal more details about the death of a 15-year-old Lubbock girl whose body was found beside a remote road.

The Lubbock County medical examiner positively identified the body Tuesday as that of Lubbock Monterey High School student Elizabeth Ennen, who had been listed for weeks as a runaway. Her body was found Monday evening along a county road near Shallowater, about 10 miles northwest of Lubbock.

The medical examiner planned to hold a news conference Wednesday morning to discuss the cause of death.

Police planned to add a murder charge to those already filed against the father of the teen's boyfriend, Lubbock police Capt. Greg Stevens said Tuesday. Humberto Maldonado Salinas Jr., 45, already was being held in Lubbock County Jail on an aggravated kidnapping charge in the case. He does not yet have an attorney, according to jail records.

Elizabeth was last seen at a Lubbock motel where she was baby-sitting Salinas' children the evening of Jan. 4 while Salinas went to play bingo and his wife went out with her sister, according to court documents.

Court documents detail motel surveillance video footage that police say shows Salinas chasing Elizabeth in a hallway, then grabbing her by the arm and forcing her toward a parking lot where his vehicle was parked. Footage then shows the vehicle leaving the motel, returning later, then leaving again.

Salinas has told investigators Elizabeth was "like a daughter" to him, according to the court records. He told investigators he took the teen home from the motel when "she started to act strange" and that he returned to her home after seeing that she'd left her purse in his car.

When he returned the purse to her house, Elizabeth's mother became suspicious and questioned Salinas, telling him her daughter was with him, the records state. Her mother reported her missing at 1 a.m. Jan. 5.