Alexander Blackman - or Marine A - has been in and out of the headlines since 2012.
Here's how his tale has unfolded.
The shooting in September 2011 came near the end of a tough tour of action in which seven marines were killed and dozens injured by the Taliban.
It took a year for the video clips of the incident to be discovered prompting an investigation.
Blackman was bought before a court martial where he was found guilty of murder.
He was sentenced to life with a minimum of 10 years.
His legal team appealed both conviction and sentence, and, after the court heard evidence he was suffering from combat stress, his prison term was cut by two years.
Despite a report by the Ministry of Defence highlighting Blackman's "unacceptably low standards", a campaign calling for a review of his case is launched led by author Frederick Forsyth.
The campaign gathers movement. Claire Blackman is joined by hundreds of former Marines, pledging their support at demonstrations outside Parliament.
Five years after the incident and three years post conviction it's announced the case will be sent to the Courts Martial Appeal Court prompting fresh calls for him to be released. On December 21 an appeal to release Marine A on bail, which would have see him return home for Christmas, is denied.