A judge has declared a mistrial against the man accused of killing a Donna High School student back in 2020.

Carlos Julian Contreras, 23, is accused in the shooting death of 18-year-old Genaro Isaiah "Izzy" Castillo on Jan. 12, 2020. Through the investigation, authorities learned Castillo and Contreras were arguing over money linked to criminal activity when the shooting happened.

RELATED STORY: Judge to consider ruling a mistrial in death of Donna High School student

The mistrial was due to prosecutors offering immunity to a witness without letting the defense know. The trial was scheduled to begin Monday after a jury was selected on September 5.

Contreras' defense team filed a motion for a mistrial on Wednesday after learning that prosecutors offered "full immunity" to a "central witness" days before a jury was selected.

A new trial is scheduled for Monday, when a new jury will be selected.