Karmelo Anthony Murder Trial Detective Says Knife in Stabbing Was Legal in Texas

The knife Karmelo Anthony allegedly used to fatally stab Austin Metcalf at a high school track meet wasn't illegal under Texas law ... according to a police detective who testified in Anthony's murder trial.

The testimony came as Anthony's defense team wrapped up its case, with jurors hearing from Detective Beau Riley -- a member of Frisco PD's Crimes Against Children unit who responded to the scene of the fatal stabbing.

One of the key moments came when Anthony's attorney had Riley confirm the knife Anthony carried that day was legal to possess in Texas ... and legal to bring into a stadium.

Riley also testified he interviewed several witnesses in the fieldhouse following the incident, including a track athlete who knew Anthony and had spoken with him under a team tent before the deadly confrontation. He told jurors he conducted a "thorough" review of the student's cellphone ... examining the teen's camera roll, text messages and Snapchat account.

The defense later called a 17-year-old track athlete who said he witnessed part of the commotion from near the stadium gates.

While he testified he had only a limited view of the bleachers, he recalled seeing a chaotic scene unfold.

He told jurors ... "Everybody was standing up and I saw somebody get pushed or get punched, I don't know which."

On cross-examination, prosecutors got the witness to acknowledge he doesn't remember every detail from that day ... and that portions of his recollection didn't fully match the video evidence.