A first-degree murder warrant was issued yesterday for a man being held on an unrelated charge in California who is suspected in the abduction and slaying of an Ocean City, Md., convenience store clerk in March, police reported.

William A. Wooten, 25, of Modesto, Calif., is named in the warrant issued yesterday in Sussex County, Del., where the body of 19-year-old Susan Riddleberger was found in her car in a trailer park near Fenwick Island, 10 miles north of Ocean City.

Wooten is being held in the Stanislaus County, Calif., jail on unrelated charges of attempted murder and attempted arson, said Jay Hancock, a spokesman for Ocean City police. Hancock said proceedings will be initiated to extradite Wooten to Delaware.

Wooten was arrested May 5 by Ocean City police on warrants issued by California authorities, was extradited to Modesto soon after and has remained in custody pending disposition of the California charges, Hancock said.

Hancock would not say what evidence led investigators to issue yesterday's warrant. A spokesman for Delaware State Police said the warrant ends an intense 5 1/2-month investigation by three agencies, including the FBI.

Riddleberger, a mother of two who lived in Parsonsburg, Md., was discovered missing from her job at a High's store on March 30. Hancock said she was abducted shortly before 9 p.m. after the store on the Coastal Highway was robbed.

After a customer notified police that the store was unattended, a search of the resort city -- fairly deserted at that time of year -- was begun. Shortly afterward, a South Bethany, Del., police officer spotted a car that fit the description of Riddleberger's car.

The officer chased the car into a trailer park where Riddleberger's body was found strangled in the back seat. The driver of the car fled on foot and disappeared into the marshes along Little Assawoman Bay.