Constable Terry began his law enforcement career in September, 1965 in Virginia. After moving to Texas in 1969, he became a patrolman with the city of Alamo Heights. He became Chief of Police for Alamo Heights in 1980, serving in that capacity for five years. While at Alamo Heights, Constable Terry attended and graduated from the F.B.I. National Academy.

In 1986, Constable Charlie Campos, Jr., of Precinct One, called on Roger as Chief Deputy, where he served for seven years. Constable Terry then transferred to Precinct Three in 1993 as Chief Deputy for Constable Bob Lew. After 14 years in this position, Constable Terry was unamimously appointed by the Bexar County Commissioner's Court on April 11, 2007, to fill the remaining term of retiring Constable Bob Lew.

Constable Terry has taught law enforcement classes at San Antonio College, Alamo Area Council of Governments, San Antonio Police Department, and many other agencies. He currently holds a Master Peace Officer Certificate and an Instructor's Certificate from TCLEOSE. Constable Terry is also licensed by the Texas Department of Public Safety to teach all levels of firearms and Security training, including Personal Protection Officer Certification. Constable Terry has served as the Traffic Director for Castle Hills First Baptist Church for over 35 years.