Officer M. Posey began his professional career by enlisting into the United States Coast Guard. During his time in the US Coast Guard, he rose to the rank of Second-Class Boatswains Mate before leaving active duty in 2015. While in the US Coast Guard he was assigned to an Anti-Terrorism Team where he was a part of several high-level security missions ranging from the protection detail of the 2008 and 2012 Presidential Inauguration, multiple United Nations Conventions, and the 2010 Olympics in Vancouver, British Columbia.

Officer Posey, while in the private sector, still had the desire to serve after leaving active duty and enrolled in Galveston College's nighttime Law Enforcement Academy. After graduation, Officer Posey began his policing career in 2019 with the Jamaica Beach Police Department as a Reserve Officer. In 2021, he left the private sector to join the department full-time as the night patrol officer. He quickly rose through the ranks moving to Detective, Warrants, and then was promoted to the rank of Lieutenant. While at Jamaica Beach, he held many qualifications such as TCOLE Certified Instructor, Marine Safety Enforcement Officer, and Field Training Officer, just to name a few. Officer Posey takes pride in helping others and serving the community as well as protecting the citizens of Hitchcock.