A Landover youth accused of murdering his 17-year-old girlfriend, who was shot Monday while taking a nap, plotted the attack because the young couple had gotten into an argument the night before, Prince George's County officials said yesterday.

At a bail review hearing yesterday, a prosecutor said that David John Head, 17, supplied the murder weapon--a handgun--to one of two friends whom he had recruited to help him carry out the slaying.

"They had an argument the night before . . . and apparently he was so angry that he solicited the murder," said Assistant State's Attorney William M. Manico.

Head, of the 3600 block of St. John Place, was ordered held without bond by District Court Judge Ronald D. Schiff. Head is charged with first-degree murder in the death of Tiffany Dionna Jackson, who was slain as she slept in her Landover Hills bedroom with their 11-month-old daughter curled up at her side.

Friends and neighbors said Head and Jackson had dated for more than three years, attended the prom together and appeared to be a happy couple. "If they were having problems, they were keeping it close to themselves--real close," said Marc Donatien, 19, who lived across the street from Jackson.

At yesterday's hearing, Schiff set bond at $150,000 for a second defendant in the case, Kyle Joseph Bruce, 18, of the 3700 block of 65th Avenue in Landover, who is charged with first-degree murder, first-degree assault and use of a handgun.

Police said Bruce drove Head and a third defendant, James McKinley Benton III, 18, of Capitol Heights, to Jackson's home in the 6900 block of Standish Drive about 11:20 a.m. Monday.

As Head and Bruce remained in the car, police said, Benton walked up to the house, pushed his way in when a child answered the front door and went directly to the back bedroom, where Jackson was sleeping with her baby daughter, Diamond. Benton woke Jackson up, then shot the young mother at point-blank range and fled with the two other suspects, police said. The baby and three other children who were in the house were not wounded.

Benton is scheduled to have a bail review hearing today. He is charged with first-degree murder, first-degree assault and use of a handgun.

Police said they have recovered the alleged murder weapon but declined to describe it or to say where they found it.

Head's attorney, Antoini M. Jones of Riverdale, denied that his client was responsible for Jackson's death. But he conceded in court yesterday that Head had told the other two defendants where they could find the handgun that allegedly was used to shoot Jackson.

In a brief interview, Jones declined to elaborate on his client's role in the case. "There was no solicitation for murder," he said. "I don't believe the evidence will show that Mr. Head had anything to do with Ms. Jackson's death. Mr. Head had no idea that would be done. He loved Ms. Jackson."

Head's parents appeared in court yesterday to speak on his behalf.

"I just want to say that all of the families are going through a hard time right now, and we're just trying to put the pieces together," said Head's mother, Claudine Head. She and her husband, the Rev. Dana C. Smith Sr., declined to speak with reporters afterward.