EDINBURG – The Hidalgo County Sheriff’s Office released details on a murder investigation in Donna.

The suspect, 17-year-old Carlos Julian Contreras, was charged with first-degree murder Thursday. Sheriff Eddie Guerra held a press conference soon after addressing the events leading up to the arrest.

On Tuesday afternoon, the body of 18-year-old Genaro Isaiah Castillo was discovered south of Donna Lake by a field worker along Valley View Road. Upon arrival, authorities saw Castillo appeared to have suffered gunshot wounds.

Sheriff's investigators found tire tracks and .40 caliber bullet casings at the scene. During their investigation, officials found out Castillo and Contreras were having an issue. They later learned it was a dispute over money linked to a "criminal enterprise," according to the sheriff.

On Wednesday, investigators located Contreras at his residence and found him in his truck. Officials found a blood-stained napkin and bullet casings inside the vehicle.

Guerra says Contreras admitted to picking up Castillo and drove the 18-year-old and another man identified as “Jorge” to the area south of Donna Lake. The sheriff mentioned they don’t believe a “Jorge” exists and Contreras acted alone. Through the investigation, authorities learned the 17-year-old was trying to purchase a firearm.

Contreras was then arrested and charged in the case. A judge set his bond at $1 million. The suspect will be tried as an adult.

The sheriff asks anyone with additional information on the case is to call the Hidalgo County Crime Stoppers at 956-668-8477.