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Sentry Security Agency was founded by J.R. (Dick) Mueller in 1969.  He started his professional career in 1955 when he enlisted in the United States Marine Corps.  In 1959, Dick went into the St. Louis Police Academy and then served as a police officer in the city of St. Louis for over seventeen years.  He started the business with a handful of friends and family.  His life-long friend, Dick Lauer, did the books and Clem and Doris Mueller performed scheduling functions and payroll.  Marlene Mueller was also on the board of directors positioned as the corporate secretary.   These founding five individuals are all life-long St. Louis natives that had a vision many years ago.

The main office was first located in the Baden area of St. Louis on North Broadway.  Later, the business moved to the Top of the Towers building in North County, then to 9901 Diamond Dr. in 1972.  In 1984, Sentry Security made its final move to 9021 Riverview Drive, where the business is currently operating.

John R. Mueller Jr. joined the business full time in 1989 after a four year enlistment in the U.S. Marine Corps.   John Mueller Jr. is currently managing the day to day operations at Sentry Security.

Dick Mueller has always kept his ties with the St. Louis City Police Department.  He has served on the board of the Police Athletic League for many years.  Dick’s son, Mike Mueller, is currently serving on the  St. Louis City Police Department for more than 29 years and was recently was promoted to Captain.  Dick’s father, Clem Mueller, also served in the U.S. Marine Corps and then returned to the City of St. Louis and served as a police officer with the St. Louis Police Department for over 37 years.

Sentry Security Agency is a family business with great values and a rich military foundation that has served the St Louis Metropolitan area for over 50 years.  With three generations of U.S. Marines and three generations of police officers, our background has really given us an advantage in this industry.  Through consistent training and a strong emphasis on customer service, our customers will always know that their needs come first.  We treat our customers like family and have built long lasting relationships with that philosophy in mind.