Davonte Washington, 15, was being raised in Maryland by his stepfather so he could have a chance to attend better schools. (Courtesy of Victor Leonard)

The 15-year-old was sitting on a bench with his mother and younger sisters inside a glass shelter, waiting for a train at the Deanwood Metro station in Northeast. Davonte Washington, his head bowed, was absorbed in his cellphone.

An older teenager clutching a white bag with carryout food walked by on the platform with friends. One of Davonte’s sisters looked at the young man after he had passed. He paused and tapped on the glass to draw Davonte’s attention.

Davonte stepped out.

They exchanged words. “What the f--- you keep looking at me for? You know me from somewhere?” the older teen uttered, police said. A split second later, without provocation or for no more reason than what the gunman may have taken as a disrespectful glance, “the suspect pulled a silver or chrome handgun and shot” Davonte, police said.

The police arrest affidavit says the gunman handed his food to a friend, tucked his gun in his pants and fled the station, with Davonte’s mother racing after him shouting: “Stop him! He just shot my son!”

D.C. Police have charged Maurice Bellamy, 17, with second-degree murder while armed in the death of 15-year-old Davonte Washington, who was fatally shot on the platform of the Deanwood Metro station the day before Easter. (WUSA9)

Police outlined a chilling scenario Tuesday in a court document as well as in a courtroom, charging Maurice Bellamy, 17, of Southeast Washington as an adult with second-degree murder while armed in Saturday afternoon’s slaying. Davonte was gunned down in front of his mother and sisters at 4 p.m. as he was headed to get a haircut for Easter, his family said.

Police said they have no evidence that the suspect and Davonte knew each other.

The lack of motive confounded D.C. Police Chief Cathy L. Lanier, long accustomed to explaining deadly violence stemming from petty disputes yet struggling to explain the District’s 26th killing of 2016.

“When it comes to violence, nothing really is more senseless than this case, in my opinion,” the chief said. “The loss of a 15-year-old boy under any circumstances is a tragedy. But in this case, it’s even more so, as it appears that there was just no reason for it. Absolutely no reason for it.”

Bellamy made his initial appearance in D.C. Superior Court on Tuesday as about 40 of Davonte’s grieving relatives watched from four rows in the courtroom, trying to comprehend the loss of the high school freshman who played Pee Wee football, aspired to join the military and was shot twice in the chest.

When marshals escorted Bellamy into the courtroom amid heightened security, Davonte’s mother yelled, “That’s the one who killed my baby!” and began sobbing as family members tried to console her. Bellamy was wearing a black hooded sweatshirt and blue jeans. His ankles and wrists were in shackles.

Victor Leonard, Davonte’s grandfather, said the family was struck by how young Bellamy looked. “He’s just a kid himself,” Leonard said.

Assistant U.S. Attorney Glenn Kirschner argued that Bellamy should remain in jail until trial. The shooting, Kirschner told the judge, “gave new meaning to the term ‘senseless murder.’ . . . This was about a 15-year-old boy who had the temerity to look at Mr. Bellamy.”

Kirschner said security video “clearly caught” Bellamy at the time of the shooting. A Metro Transit Police officer identified Bellamy from a mug shot matched to the surveillance video. Two witnesses with Bellamy also identified him, Kirschner said.

According to documents obtained by The Washington Post, Bellamy was arrested in 2014, when he was 16, for simple assault and for threatening an employee of Ballou High School, where he was a freshman.

Bellamy’s attorney in the Metro shooting, Madeline Harvey with the District’s Public Defender Service, argued that the witnesses may have been biased and could have been threatened by police to identify Bellamy or face arrest themselves. “We don’t know what the police said to them,” she said. Bellamy’s relatives left the courtroom without speaking publicly.

Magistrate Judge Renee Raymond found Bellamy to be a danger and ordered him held at the D.C. jail until his next hearing, scheduled for April 22. Court documents say that Bellamy lived in a group home in Northwest Washington and grew up in the Kentland community in Prince George’s County. Police said they traced him to a Facebook page with pictures of him labeled, “SHOOTA MOE, AKA MOE CITY.”

According to the documents obtained by The Post, Bellamy was arrested in May 2014 after officials said he threatened a Ballou staffer who told him to leave a hallway. The staffer ordered Bellamy again to leave the hallway, the documents state, and Bellamy allegedly swung his fist and had to be restrained. He reportedly threatened to return to the school and “smoke all you . . . . ”

Bellamy pleaded guilty to misdemeanor threats, was placed on three months’ probation and ordered to undergo anger management classes and random drug testing for marijuana. He told a therapist that he had begun using marijuana when he was 14.

The documents show that he continued to miss school and the drug tests and failed to meet with his counselor. A probation officer’s recommendation to put him in a youth detention center was rejected by a judge, and he was put on probation again.

Davonte was reared in Maryland to give him a chance to attend better schools, a decision that meant living with his stepfather and apart from his mother and sisters in the District. He played for the Pepper Mill Boys and Girls in 2010, where his coach, Darnel Dorsey, described him as a “great athlete,” adding that he “was liked by everybody and wasn’t a troubled kid.”

Leonard said his grandson joined the Navy ROTC when he entered Largo High School and was leaning toward a career in the military.

“He was very humble,” Leonard said. “He understood if his parents couldn’t afford something and couldn’t keep him in the latest style. He wasn’t a kid who had to have the latest and greatest. He accepted what was given to him by his parents.”

The grandfather said he talked to Davonte on the phone the night before the fatal shooting. He was excited to spend the weekend with his mother and sisters, see cousins and visit an aunt. Just before hanging up, he told Leonard, “I need to get a haircut for Easter.”

They ended the conversation with the same words they say that everyone in the family uses to greet each other and say goodbye: “I love you always.”

Lynh Bui, Dana Hedgpeth, Jennifer Jenkins and Hamil R. Harris contributed to this report.