Described by Circuit Court Judge Joseph Bulone as a "wanna-be" police officer and a self-appointed "handicapped parking space monitor," Drejka confronted McGlockton's girlfriend, questioning why she parked in a handicap-reserved parking space without a permit.
During the initial encounter, McGlockton was inside the store with his 5-year-old son. When he left the store, he shoved Drejka to the ground, surveillance video showed.
Drejka then pulled out a Glock .40-caliber handgun and shot McGlockton in the chest. He later told investigators he was in fear of a physical threat to his safety.
McGlockton died at a hospital 30 minutes later.
The shooting brought national attention to Florida's controversial "Stand Your Ground" law, which, since enacted in 2005, established the right for gun owners to apply lethal force to defend themselves against threats regardless of whether it was possible to retreat first.
Pinellas County Sheriff Bob Gualtieri initially did not arrest Drejka, saying the controversial law precluded him from doing so. Three weeks passed before Pinellas-Pasco State Attorney Bernie McCabe announced that his office was formally arresting and charging Drejka with manslaughter.
The case touched on race, given that Drejka was white and McGlockton was black.
Drejka on Thursday was sentenced to two decades in prison, with credit for 92 days served, WTVT reported. He faced up to 30 years behind bars.
Fox News' Danielle Wallace and The Associated Press contributed to this report.