History

ACF Alarm is a proud subsidiary of Sentry Security, a company built on service, integrity, and a strong St. Louis legacy.

Sentry Security Agency was founded in 1969 by J.R. (Dick) Mueller. His professional journey began in 1955 when he enlisted in the United States Marine Corps. After completing his service, he entered the St. Louis Police Academy in 1959 and went on to serve as a St. Louis City police officer for more than seventeen years.

Sentry Security began as a small, family-driven operation. Dick’s lifelong friend, Dick Lauer, handled the accounting; Clem and Doris Mueller managed scheduling and payroll; and Marlene Mueller served as Corporate Secretary on the Board of Directors. All five founders were St. Louis natives who shared a vision and the dedication to build a trusted local security company.

The company’s first office was located in the Baden area of North St. Louis on North Broadway. It later moved to the Top of the Towers building in North County, then to 9901 Diamond Drive in 1972. In 1984, Sentry Security relocated to its permanent home at 9021 Riverview Drive, where operations continue today.

John R. Mueller Jr. joined the company full-time in 1989 following his four-year service in the U.S. Marine Corps. He now oversees the day-to-day operations of Sentry Security.

Dick Mueller has remained closely connected to the St. Louis Police Department throughout his life, serving on the board of the Police Athletic League for many years. His son, Mike Mueller, has been with the St. Louis City Police Department for over 29 years and was recently promoted to Captain. Dick’s father, Clem Mueller, also served in the U.S. Marine Corps before returning to St. Louis to complete a 37-year career with the St. Louis Police Department.

Sentry Security Agency is, at its core, a family business grounded in strong values and a proud military and law enforcement heritage. With three generations of U.S. Marines and three generations of police officers, our foundation has shaped who we are and the standard of service we provide. For more than 50 years, we have served the St. Louis Metropolitan area with a commitment to professionalism, rigorous training, and exceptional customer care.