Jamarion Lawhorn pleaded not guilty Tuesday afternoon in Kent County Family Court. WZZM-TV is identifying the minor because he is being charged as an adult.
Lawhorn is accused of repeatedly stabbing Michael Conner Verkerke in the back at the Pinebrook Village mobile home park Monday evening.
Neighbors said Conner, as he was called, ran screaming to his home and collapsed bleeding on his porch. He died later Monday evening at a hospital.
Lawhorn used a neighbor's phone to call 911 and turn himself in. He was arrested and taken to the Kent County Juvenile Detention Center.
"We were sitting on our deck," said Barb Poelman, 60. "We heard the kids run across the front ... screaming. (Conner) ran with the kids that were with him."
A little later, Poelman said the boy's distraught mother lay on the grass outside the family's home in Kentwood.
"She was screaming, 'Where is the ambulance?' while her boy was laying on the porch bleeding," Poelman said. "The kids, I thought they were just playing."
Witnesses told investigators that four children were playing when Lawhorn, for unknown reasons, pulled a knife and stabbed the boy.
Glen Stacy, who lives nearby, described Lawhorn after the stabbing as "very calm."
"The only time he raised his voice was when the police came," Stacy said.
The motive in the attack was still being investigated, said Kentwood Police Chief Thomas Hillen. Police said Lawhorn was evaluated at a hospital before being taken to the Kent County Juvenile Detention Center.
Family and friends are planning a candlelight vigil at the playground for 7 tonight to memorialize Conner.
In court Tuesday, Lawhorn's defense attorney asked for a competency evaluation to make sure he understands the case against him. The boy will be tried in family court and could be given an adult sentence, but will not receive a mandatory life sentence because of recent changes to the law.
The Associated Press contributed to this report.