San Antonio Police Officer Arrested For Assault
A 25-year veteran of the department faces a charge of aggravated assault with a deadly weapon.
Updated on Oct. 16, 2026 in Law Enforcement
The San Antonio Police Department arrested veteran officer Mark Castillo on Friday following an investigation into an alleged assault. Castillo, who is assigned to the patrol division, was off duty during the incident on September 26.
Why it matters
The arrest of a long-term officer highlights the internal and criminal accountability processes within the San Antonio Police Department. Following the arrest, the department has placed the officer on administrative duty while multiple investigations proceed.
Mark Castillo is currently awaiting booking into the Bexar County jail after being arrested on a warrant. The officer has been placed on administrative duty pending the outcome of internal and criminal investigations.
The players
Mark Castillo
He is a 25-year veteran of the San Antonio Police Department assigned to the Patrol Division.
San Antonio Police Department
This is the primary law enforcement agency for the city of San Antonio responsible for investigating the conduct of its officers.
The details
Castillo, who has served for 25 years, was taken into custody on an active warrant stemming from an event that occurred while he was off duty. He is currently being processed by the department as investigators review the details of the alleged assault.
Timeline
September 26, 2026: The alleged assault took place.
October 16, 2026: Officer Mark Castillo was arrested on a warrant.
Legal Context
This case follows a pattern of heightened administrative and criminal scrutiny applied to law enforcement officers accused of off-duty misconduct. Similar cases are often prosecuted under standardized state penal codes governing the use of deadly weapons.
The arrest of an officer does not immediately alter daily police operations in the local neighborhood. Residents should monitor official police releases for updates on potential impacts to community safety or changes to patrol staffing.
The takeaway
Officers are subject to the same criminal justice procedures as any other citizen when accused of violent crimes. Maintaining public trust requires transparency and consistent enforcement of policies during internal investigations.
Further reading
For more information on departmental oversight, visit the Law Enforcement section.
