A 23-year-old man, who police allege tossed his 3-month-old nephew into a ceiling light fixture during a drug-induced hallucination, pleaded guilty yesterday to second degree murder in connection with the death of the baby, who suffered a fatal skull fracture.

Thomas S. Jenkins, a commercial scallop fisherman, had been smoking the drug phencyclidine (PCP) and reading the Bible in his sister's Annandale home last Nov. 20 before he walked into the bedroom where the baby, Jonathan O. Dyer, was sleeping, police investigator Bill Mullins said during a hearing yesterday in Fairfax County Circuit Court.

"He threw the baby up and his head struck a light on the ceiling," Mullins testified. The parents, who had been sleeping in the living room, found the baby crumpled on the floor minutes later, Mullins said.

"I killed the devil," Jenkins told the parents, Diane and Bruce Dyer, after the incident, according to court records from an earlier hearing. Police said in court yesterday that Jenkins apparently was hallucinating after using PCP.

"He Jenkins said he tripped out and killed his sister's baby," Mullins told Judge Barnard F. Jennings.

Jenkins pleaded guilty to second degree murder after prosecutors reduced the charges from first degree murder. Commonwealth's Attorney Robert F. Horan Jr. said the charges were reduced because Virginia law stipulates that premeditation is a requirement for a first degree murder conviction.

"Voluntary intoxication including drug use can excuse the premeditation factor," Horan said. "But, it does not excuse the murder."

Second degree murder carries a prison term of five to 20 years. Jennings scheduled sentencing for July 1. Jenkins' court-appointed attorney, Warren W. McLain, said others in the house apparently had been smoking PCP with Jenkins the night the death occurred.