The 18-year-old suspect in the stabbing death of Frisco, Texas track star Austin Metcalf was indicted by a grand jury Tuesday for first-degree murder. 

“For weeks, my team has been presenting evidence to the grand jury. Today, I summarized that evidence, and I asked the Grand Jury to return a first-degree murder indictment against Karmelo Anthony — which they did,” Collin County District Attorney Greg Willis said. 

“With that indictment, the case now moves formally into the court system,” he said. “From this point forward, we’ll continue doing our part — fully and fairly — to pursue justice under the law. The trial schedule will be set by the court. But when the time comes, we’ll be ready.”

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

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

The witness told the officer that Anthony deserted the scene following the stabbing. Metcalf died in his twin brother’s arms.

Anthony allegedly told the responding school resource officer, who cuffed him upon arrival at the scene, that he was protecting himself. The officer also noted blood on Anthony’s left middle finger. 

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.”

Accused killer Karmelo Anthony walks out of jail after posting bond. (KDFW)

After initially being held on $1 million bond, Anthony’s bond was reduced to $250,000, and he was released to home confinement. A trial date has not yet been set. 

The Anthony family’s spokesperson did not immediately return a comment request. 

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