The attack was ‘predatory in nature’, prosecutor Keith Brown told a judge on Monday at a family court hearing attended by the boy. A police detective testified that the suspect showed no remorse while confessing to the crime.
Police originally suspected Minghui Yu, 24, was the victim of a robbery Friday night as he walked home from his girlfriend's apartment. But two other boys who were with the suspect at the time later told investigators it was a crime of impulse, police said on Monday.
"Watch what I do to this guy," the attacker said before pouncing on Yu, according to the other boys. The suspect himself insisted he had been egged on by his friends, police said.
Authorities allege Yu's assailant grabbed and struck him several times on a street median. When Yu broke free and ran across a southbound lane, he was struck by a sport utility vehicle.
Yu was pronounced dead at a hospital. The driver of the car was not charged.
Police were able to identify the suspect by studying footage from a security camera that showed the three boys fleeing the scene on foot.
The suspect, whose name was not released because he was a minor, appeared to fight back tears on Monday as the judge decided to lock him up in a juvenile detention facility until his next court date on Thursday.