On Monday night, 12-year-old Jamarion Lawhorn calmly walked up to a man working in a yard in Kentwood, Mich., and asked to borrow a phone.

“Hi. I just stabbed somebody. Please pick me up. I want to die. I don’t want to be on this Earth anymore,” the boy reportedly told a 911 dispatcher.

Minutes earlier at a neighborhood playground, Jamarion had allegedly pulled out a knife buried in the sand and repeatedly stabbed 9-year-old Michael “Conner” Verkerke in the back. Conner ran home screaming and collapsed, bleeding on his porch, according to neighbors and police.

Soon, his mother was screaming, too.

“She was screaming, ‘Where is the ambulance?’ while her boy was laying on the porch bleeding,” neighbor Barb Poelman told the Detroit Free Press. Conner died not long after he was transported to a local hospital Monday night, Kentwood Police Chief Tom Hillen told the Grand Rapids Press. The motive for the killing is still unclear.

Jamarion, who is charged with murder as an adult, pleaded not guilty Tuesday afternoon, according to news reports. WOOD-TV reported that he is one of the youngest ever charged with murder in Michigan and the youngest in Kent County. (The Washington Post is naming him because he is charged as an adult.)

This “route was taken because if a juvenile is charged as a juvenile in juvenile court, the judge would have no option but to discharge at the age of 21,” Assistant Kent County Prosecutor Laura Clifton told the Free Press in an e-mail Tuesday. If the boy is convicted, Clifton said, a judge will review his case every three months and could impose an adult sentence at any time. If an adult sentence is not imposed by the time he turns 21, the judge must either discharge him or impose the sentence then.

Clifton said Jamarion’s attorney requested a competency examination. He is being held without bond in the Kent County Juvenile Detention Center.