Mizanskey was originally sentenced to life in prison without parole for marijuana possession in 1996.
Gov. Jay Nixon announced in May that he had agreed to commute Mizanskey's sentence after the story gained national attention.
Mizanskey was then able to argue his case in front of a parole board in August, and he was subsequently granted parole.
Mizanskey had multiple previous drug convictions prior to his 1996 conviction.
In 1984 he was convicted of possession and sale of marijuana, and in 1991 he was convicted of marijuana possession.
Mizanskey was also arrested for possession of a variety of drugs in 1983, and served a 60-day jail sentence.
His life sentence came as a result of a three-time drug conviction.
The prosecutor in the case had written a letter to Nixon supporting
supported clemency, although his letter also detailed a history of
criminal violations by Mizanskey.
A Missouri House bill that would authorize the release of any
offender serving a life sentence without parole for marijuana offenses
was introduced during the legislative session in February, but it failed