Karmelo Anthony, the 17-year-old suspect in the stabbing death of Frisco, Texas track star Austin Metcalf, cannot face the death penalty or life without parole, according to Collin County District Attorney Greg Willis. 

Willis explained to WFAA that prosecutors cannot seek the death penalty or life without parole because of a Supreme Court ruling in a case called Roper v. Simmons from 2005, that excludes juveniles from those punishments. 

“The Supreme Court has said not only can you not seek the death penalty against someone who committed a crime when they’re 17, you can’t even get them life without parole,” he said. “That would not be something we could do even if we wanted to.”

Karmelo Anthony, 17, was arrested and charged with first-degree murder. (FOX 4)

16-year-old Austin Metcalf died at his track meet on Wednesday after being stabbed. (FOX DFW Chopper)

Metcalf reportedly told Anthony that he needed to move out of the Memorial team’s tent, a witness told Frisco police. The report noted that Anthony “grabbed his bag, opened it and reached inside it” and said, “Touch me and see what happens.”

Metcalf then pushed Anthony out of the tent, according to the report. 

In the next moment, the witness told police that Anthony “reached into his bag and the male took a knife out of the bag and stabbed Austin.”

A school resource officer was the first to respond to the scene, and handcuffed Anthony, noting that there was blood on the suspect’s left middle finger. 

Mugshot of Karmelo Anthony, left, and Austin Metcalf in football pads, right. (Fox DFW/Jeff Metcalf)

“I was protecting myself,” Anthony said. “He put his hands on me.”

One officer at the scene referred to Anthony as the alleged suspect, and Anthony made a “spontaneous statement,” according to the report: “I’m not alleged, I did it.”

Anthony also asked the officers if Metcalf was “going to be OK” and asked if what happened could be considered “self-defense,” the report said.

Fox News’ Sarah Rumpf-Whitten and Brooke Taylor contributed to this report.