A preliminary autopsy report showed yesterday that the 2-week-old infant whose body was taken from the Shenandoah River Tuesday in a plastic garbage bag died of asphyxiation and head trauma, West Virginia State Police said.

The infant's mother, 21-year-old Kathleen Householder of Rippon, W.Va., was charged late Tuesday with murder in the death of her daughter. A bond hearing for Householder, who is being held in the Jefferson County, W.Va., jail, is scheduled for Feb. 3 in County Circuit Court.

Authorities say they now believe the infant, Lindsey Blake Householder, was killed Jan. 3 in West Virginia and taken to Virginia, where her body was dumped in the river in Clarke County, near the Rte. 50 bridge. An exact time of death has not yet been confirmed, said West Virginia State Police Cpl. Greg Stevens.

The mother, who officials say has no prior conviction in West Virginia, first said the child had been taken from her pickup three weeks ago while it was parked outside a supermarket in Winchester, Va.

In the following days, she made a series of appeals in the newspapers and on television for the infant's return. A $15,000 reward was offered by the National Missing Child Search Society for information leading to the baby's recovery.

Householder changed her story on Monday after submitting to a lie detector test, police say. She accompanied police on Tuesday's search for the body, which was found about 200 yards downstream from where she had told them it would be, authorities say.

Her husband, Daniel, a 21-year-old construction worker, was at his job near Washington the day the child was reported missing, and is not a suspect in the case, police say. He had no comment yesterday. The couple's other child, Dustin, 2, is staying with relatives, officials said.