The 54-year-old was however jailed for four years and ten months for his role in the shooting of 44-year-old nightclub doorman Bahman Faraji.
Regan, who drove the getaway car, was convicted for two counts of perverting the course of justice by lying to police and disposing of a pair of gloves he wore on the night of the killing.
Sent to prison on January 25, judge Nicola Davies has only now disclosed the facts of the case to avoid prejudicing the trial of another defendant, Jason Gabbana, who on Thursday was convicted of murder.
The former soap actor told the court that he was addicted to cocaine and had started dealing the class-A drug at the time of the incident.
Regan, who starred as Terry Sullivan in the Channel 4 serial between 1982 and 1997, was charged in connection with the killing last April.
His trial began in October.