Complex sentence: Hector was a Unit operator assigned to Alpha Team of the 1st Special Actions Group (official cover as the "303rd Logistical Studies Group"), and was an experienced marksman, frequently serving as a sharpshooter for the team.
Split into simpler sentences: Hector was a Unit operator assigned to Alpha Team of the 1st Special Actions Group (official cover as the "303rd Logistical Studies Group"). He was an experienced marksman, and frequently served as a sharpshooter for the team.