D.C. police patrol outside the Woodley Park Metro station where Olijawon Griffin, 18, was fatally stabbed after a dispute with teenagers who had robbed him earlier Saturday. (Marvin Joseph/The Washington Post)

Olijawon Griffin graduated from high school and took a job at the National Institutes of Health as a driver while thinking about college to study sports medicine. He used one of his first paychecks to buy a black Helly Hansen jacket.

D.C. police said the 18-year-old was robbed of that designer jacket early Saturday while out in Adams Morgan and was fatally stabbed less than 90 minutes later in the Woodley Park Metro station after seeing a youth wearing his jacket.

“It’s crazy that he was robbed for a jacket,” said Sukaina Poitevien, who lives next door to Griffin’s family in Olney. She helped organize a candlelight vigil Monday night at which hundreds gathered in a circle around Griffin’s family and comforted each other.

While the victim’s family mourned, prosecutors on Monday charged a 17-year-old from District Heights as an adult with second-degree murder while armed. Eight other youths — shackled at the ankles and wrists — sat through a preliminary hearing in juvenile court.

Authorities said Chavez Tyrek Myers, who also is charged with assault with a deadly weapon, was ordered detained until his next hearing. Court documents allege that he snuck up behind Griffin during a fight at the Metro station and plunged a knife into his chest.

The charges filed against so many defendants in adult and juvenile courts prolonged the proceedings, with a juvenile hearing starting in early evening and lasting into the night for two 15-year-olds, two 16-year-olds and four 17-year-olds.

Magistrate Judge Diana Harris Epps agreed with prosecutors to continue the hearing to Monday, to give authorities more time to build their cases. A prosecutor said most of the nine witnesses have not been interviewed, and video and audio from the Metro station needs to be digitally enhanced. Defense attorneys argued that the charges were too broad and did not say what each defendant allegedly did.

The Washington Post and other news media were allowed to attend part of the juvenile proceedings but were barred from reporting names or other identifying traits. Epps barred reporters from hearing probation reports, which can detail juvenile and school records, as well as personal information about parents.

According to court documents made public at Myers’s arraignment, Griffin went into an alley in Adams Morgan to buy marijuana from a group of young men shortly after midnight Saturday. A few minutes later, he was robbed at gunpoint of his jacket, an iPhone and tennis shoes, documents indicate.

Griffin and two friends later walked to the Woodley Park Metro station to head home, according to the court documents. The people who had robbed him, part of a group as large as 12, were on the platform, police said.

One of them, the court documents say, was wearing Griffin’s jacket.

“Give me my jacket back!” Griffin said.

Members of the larger group attacked one of Griffin’s friends, according to the documents.

“They swarmed him,” D.C. police homicide Detective Carter Dwight Adams testified in the juvenile proceedings. “They were kicking him and hitting him over and over again.”

Griffin and the other friend rushed toward the station manager’s kiosk, the court papers said, but then Griffin went back to help his friend on the platform.

According to the court documents, a police officer who watched Metro security footage saw Griffin engage one teen in a boxing-style fistfight shortly after 1:15 a.m. and then saw Myers sneak behind Griffin with a knife, stab him in the chest and run.

Griffin was pronounced dead at a hospital about 2 a.m.

Myers told detectives that the stabbing was in self-defense, according to court papers. He denied a role in the robbery but acknowledged attacking one of Griffin’s friends on the Metro platform, court documents said.

Griffin, a 2012 graduate of Sherwood High School in Sandy Spring, was a linebacker on the school’s football team. Marc K. Thomas, one of Griffin’s former coaches, described him as someone who would “run through a brick wall for his team and his fellow players.”

Griffin had worked since late last month as a contract driver’s assistant in the Waste and Resource Recovery Branch of the National Institutes of Health’s Office of Research Facilities, according to an agency spokeswoman.

At the vigil Monday evening, anti-violence advocates and relatives of Griffin begged the crowd not to seek revenge.

“I don’t want any of you to be angry at anybody,” said Ishmael Gaynor, Griffin’s cousin.

For others in the family, it was time to let out all the grief.

“I’m so hurt and distraught,” said Isaiah Hollins, Griffin’s brother. “I hope everything goes right and [the judicial system] prosecutes them to the fullest.”

In an interview on WJLA-TV, Lunette Griffin urged authorities to charge more of the suspects as adults in her son’s killing.

Her son stood “6-foot-1, weighing 200-and-something pounds,” she said in the interview. “Without their help, Olijawon wouldn’t have been stabbed.”

Michael Laris and Martin Weil, and St. John Barned-Smith of the Gazette, contributed to this report.