Garrison's sentence stemmed from a December 2006 drunken driving crash in which he drove his Land Rover into a tree and killed Vahagn Setian, 17. The crash also injured two teenage girls. At the time, Garrison pleaded guilty to vehicular manslaughter, misdemeanor counts of drunken driving and giving alcohol to a minor.
In October 2007, Garrison was sentenced to 40 months in jail, four years' parole and a to pay nearly $300,000 in restitution to the victims and their families.
A civil lawsuit filed by Setian's family and another injured party was settled recently. No details of the settlement have been disclosed.
Now that he has been released, Garrison plans to devote some of his time toward cautioning young people against drinking and driving. "He will never forget what happened and he will have to learn to the live with guilt," his lawyer, Harland Braun, told PEOPLE earlier this month. "When he gets out, he will talk to teenagers as a volunteer."