I tend to think that the fact that the Foriegn and Commonwealth Office have said that, after a lengthy investigation, they believe a major miscarriage of justice has occured, that there is a very good chance that he’s an innocent man.
It does look to someone unfamiliar with the US justice system, outside of TV and movies, weird that the courts won’t hear new evidence (e.g. the 5 alibi witnesses that have come forward).
At least he’s not facing the death penalty. (This sort of case is one example of why I abhor the deah penalty). While the linked article says that some people alibi him, it doesn’t go on to say that those alibis have been investigated and proven.