Police say Julio Castro approached officers the next day and admitted he shot David Alai Rodriguez Cabrera.
SAN ANTONIO, TX — A 36-year-old San Antonio man was charged with murder after police said he admitted shooting and killing his roommate Friday afternoon behind a West Side home.
Julio Castro was arrested Saturday in the death of David Alai Rodriguez Cabrera, also 36, after investigators tied him to a shooting in the 900 block of South San Augustine Avenue, near Castroville Road. Police said the case moved quickly after Castro approached officers who were handling an unrelated call and said he wanted to turn himself in.
The shooting was reported around 2:45 p.m. Friday after several people called police to report hearing about five gunshots. Callers also told dispatchers they saw a man lying on the ground and another man in black walking away from the area. When officers arrived, they found Rodriguez Cabrera dead in the backyard with multiple gunshot wounds, according to an arrest affidavit.
Investigators found several spent .357 shell casings at the scene and recovered a Glock Model 31 .357-caliber handgun, the affidavit said. Police also found a letter addressed to Castro at the home. A nearby witness told detectives they heard gunfire, went outside and saw Castro walking away from the residence. Surveillance video later showed Castro and Rodriguez Cabrera together in the backyard moments before the shooting, with no clear fight or struggle visible, according to the affidavit.
Police said Castro first told investigators that Rodriguez Cabrera had brought him food and that he wanted to show him how the gun fired. Castro said he leaned back and one shot went off, striking Rodriguez Cabrera. He later gave a different account, saying he shot his friend after an argument because he felt Rodriguez Cabrera was going to shoot him. Officers said Rodriguez Cabrera did not have a gun on him when he was found.
The next day, Castro flagged down San Antonio police officers and told them he had done something while on narcotics, investigators said. After officers confirmed a shooting had happened at the address Castro described, they read him his Miranda rights. Police said Castro confirmed details of the shooting and told them he had retrieved the gun from inside the residence before the shooting.
Castro was taken to San Antonio Police Department headquarters Saturday. Police said he later declined to answer more questions without an attorney. He was booked the same day into the Bexar County Adult Detention Center on a murder charge. Court records listed him as the suspect in Rodriguez Cabrera’s death.
The relationship between the two men was described by police as both friends and roommates. Investigators have not released a final motive. The affidavit points to Castro’s statements, witness accounts, surveillance video, shell casings and the recovered firearm as key pieces of evidence in the case.
The case remains under investigation by San Antonio police. Castro’s next court date had not been publicly detailed as of Monday, and prosecutors are expected to review the evidence as the murder case moves through Bexar County court.
Author note: Last updated June 22, 2026.