The teen told the judge in court Monday, "I was frustrated. Hit the ref. And caused his death."
The 17-year-old was charged after an incident on April 27. The teen punched Portillo at a soccer match at Eisenhower Junior High in Taylorsville. After a week in coma, Portillo died.
The judge ordered the teen to remain in custody at a juvenile detention center until he is 21. The minor must keep a photograph of Portillo on his cell wall. The minor must also write a letter to the Portillo family every week.