The 19-year-old gunman accused of killing teenage peacemaker Mahlik Brown as the high schooler was trying to deescalate a tense standoff in SoHo last week was identified in part by his uniquely colored sneakers, prosecutors said Saturday.

Baby-faced murder suspect Henry Thomas was wearing a distinct pair of black Air Jordan sneakers with red and yellow trim when he fatally shot victim Mahki Brown on May 7, prosecutors said.

Thomas was caught on surveillance camera sitting in the basket of a Citi Bike rolling into the courtyard of the luxury Dominick Hotel on Spring St. near Varick St., his legs dangling over the side, just before the shooting.

Mahki, 16, was trying to break up a fight between three girls who attended his charter school, the Broome Street Academy when Thomas jumped out of the basket and fired three rounds into the crowd.

Thomas’ bullets hit Mahki twice in the legs and once in the head, prosecutors said during an arraignment hearing at Manhattan Criminal Court, where the suspected shooter was ordered held without bail.

“The defendant executed a 16-year-old high school student by shooting him in the head in front of a crowd of students,” Manhattan Assistant District Attorney Gina Nerone said.

Thomas and his accomplice, who remained at large Saturday, split up after firing the shots.

Using surveillance video recovered from nearby buildings, detectives were able to backtrack their movements all the way to Avenue D on the Lower East Side, more than two miles from the shooting.

While Thomas was wearing a surgical mask and a black hoodie at the time of the shooting, Thomas wasn’t wearing a mask in the footage recovered on the Lower East Side but was still sporting his snazzy sneakers, prosecutors said.

Cops also collected video that showed Thomas pedaling off on the Citi Bike moments after the shooting, officials said. He rode it into the West Village, where he ditched the bike and jumped into a cab that took him back to Avenue D.

Detectives learned Thomas lived in an Avenue D building near where he and his accomplice picked up the Citi Bike, but the murder suspect was “hiding out” at a relative’s apartment on Lenox Ave. in Harlem, when cops found him Friday morning, Nerone explained.

Executing a search warrant at his Avenue D home, detectives recovered the colorful sneakers he wore during the murder, Nerone added.

Police charged Thomas with murder and weapons possession. He’s never been arrested before, but cops did detain and question him on March 23 for riding in a stolen vehicle near his home, officials said. Detectives used body camera footage of that interview, where Thomas gave his name, date of birth and address to police, to help identify him.

Thomas, dressed in a gray sweat suit with a dark gray strip running down the pant legs, said very little as he was brought before Judge Marisol Martinez Alonso Saturday.

More than a dozen of Thomas’ relatives watched the proceeding in the gallery, but refused to talk to the press.

“He’s innocent,” one relative declared as he left the courtroom.

Thomas’ attorney Adam Freedman objected to Nerone’s use of the word “executed” during the hearing.

“Things like ‘executing’ and ‘hiding out’ is what they assume evidence will show,” Freedman said, adding that the jury may come to a different conclusion.

“Some of the language they used in trying to describe this was prejudicial and inappropriate for a bail application,” he told the Daily News following the hearing. “The allegations are very serious. My client is determined to fight the charges and that’s what we’re going to do.”

Mahki’s murder is the latest in a recent spate of teen killings to hit the city. On May 2, Emery Mizell, 17, was stabbed to death in the courtyard of a Bronx apartment building. A 15-year-old girl was charged with murder.

A week later, Sara Rivera, also 17, was fatally knifed outside the 46th St.-Bliss St. subway stop in Sunnyside, Queens. Police arrested a 15-year-old classmate and charged her with the teen’s murder.

Eight people under 18 have been murdered in the city as of Thursday, police said. It’s a drop from this time last year, where 11 children under 18 had been killed.

It’s not believed Thomas intended to harm Mahki when he fired off the shots, a police source said.

Friends said Mahki was simply trying to diffuse a tense situation when he was caught in the crossfire.

“That’s who he was. I think it’s just his upbringing, because if his mother can help you, she’ll help you,” neighbor and family friend LaKesha Jenkins, 48, told The News Friday. “Children, they’re taught by their parents. It’s just something that he learned watching his parents help people when they could.”