Robert Langdon initially received a death sentence in 2009 but always maintained his innocence, claiming he killed in self-defence. His family, after spending years campaigning for his freedom, received the news this week that a presidential pardon had been granted and he was on his way home.
"He certainly has been released and the family, of course, are very very pleased about that," family lawyer Stephen Kenny said.
Mr Langdon was initially convicted for shooting Afghan colleague Karimullah, when a dispute arose while they were escorting a convoy to an American military base in mid-2009. He was found guilty of killing the man, and then trying to blame the murder on a Taliban ambush.
The Australian was also accused of setting fire to the dead man's body and trying to flee the country. Mr Langdon was sentenced to death but later had his sentence reduced to a 20-year jail term after his family reportedly paid the family of the dead man a substantial sum of money in compensation.