With a cheering Forestville High School student body looking on, Rico Marshall, a senior running back, signed a national letter of intent to play football on a full scholarship at the University of South Carolina. That was Wednesday.

Thursday night, Marshall, who often sang the national anthem at home games, won the school's talent contest with his rendition of singer Luther Vandross' "The Other Side of the World."

"He was really on the top of the world Wednesday," said Forestville football coach Eric Knight. "And Thursday, Rico was so proud."

Saturday at 4:10 a.m., the soft-spoken 18-year-old, whom friends described as "extremely popular," was pronounced dead. Prince George's County police said a girlfriend told them Marshall had swallowed about six chunks of crack, a cocaine derivative.

"He didn't deserve this," said teammate Leslie Shepherd, an All-America wide receiver who signed with national champion University of Miami at Wednesday's assembly.

"This is a tragedy beyond comprehension," said Forestville Principal Paul Lewis. "Everyone liked Rico, and he crossed the boundaries with all the people in school -- the athletes, the smart kids, the staff, everyone. His death will have a devastating effect on our school and students."

Lewis described Marshall as a student who "kept order rather than caused disorder."

Dr. John E. Smialek, chief Maryland medical examiner, said the cause of Marshall's death hasn't been determined. Tests are expected to be completed by Friday, he said.

A police investigation is under way, authorities said. According to preliminary accounts by police, Marshall told an 18-year-old girlfriend he swallowed the drug as police officers approached him about 1:30 a.m. in the 1400 block of Nova Avenue in Capitol Heights, an area known for drug trafficking.

A school faculty meeting is scheduled for 8 a.m. tomorrow to discuss Marshall's death. At 9 a.m., Knight is to meet with the football team. The school will be closed today for George Washington's birthday.

"I'm really worried about all those other kids, making sure they are all right," Knight said. "There are going to be some kids who are really hurting Tuesday. There are some kids really hurting now, but they will be hurting even more Tuesday."

The 5-foot-11, 205-pound Marshall, whose brother Marc, 16, is a junior defensive end at Forestville, rushed for 1,026 yards and scored 10 touchdowns this past season. He was an honorable mention All-Met selection.

At the family's Landover apartment yesterday, relatives and friends said that Marshall had tried to avoid what they termed the "drug-infested" environment outside his home. The sprawling Glenarden Apartments complex consists of two- and three-story garden apartments, many of them boarded up. Some yards are strewn with litter.

"Rico hated the situation here," said his mother, Carolyn Marshall, an assistant catering manager. The youth previously lived with his family in Forestville.

On a table, a large yellow cake was untouched in a cardboard box. The cake, given to Marshall by a friend for his 18th birthday Tuesday, was decorated with a likeness of his favorite singer, Whitney Houston.

Marshall's parents continued to dispute reports linking his death to drug involvement. Cradling an autographed football given to his son when he surpassed 1,000 yards rushing, Leroy Marshall, a youth counselor, said, "My son is an athlete. He hated drugs."

Carolyn Marshall said reports of drug involvement would be difficult to accept. "It would be something shocking and devastating. I thought I knew my son better than that."

County Fire Department spokesman Tony DeStefano yesterday disputed a claim by Marshall's father that ambulance crews were slow in responding. According to department logs, DeStefano said, the first of several calls was received at 3:08 a.m. and emergency crews arrived in 10 minutes. DeStefano said a caller told the dispatcher that "there was a violent overdose" at the apartment. Staff writer Donald Huff contributed to this report.