Powell, who was sentenced to nine months' imprisonment for failing to hand over his firearm to the police, was released last Tuesday, after serving just under six months.
Joyce Stone, deputy commissioner - Custodial Services at the Department of Correctional Services, said that a third of the sentence for a first-time offender is set aside as remission for good behaviour.
Investigators had wanted Powell's Glock pistol to help their probe into the murder of 17-year-old Khajeel Mais in July 2011. Mais was killed in a reported act of road rage in Havendale, St Andrew.
Powell was found not guilty for the murder of Mais. But a High Court judge last October ordered that he pays $2 million to the family of slain Kingston College student, arising from a wrongful-death lawsuit.