Thought I'd Moat this one up again since I've now watched the series.
My feeling is that the guy might be innocent and at the very least there are some massive question marks over the police handling of the whole thing. A lot of the evidence is pretty sketchy, especially the stuff around his blood in the car, the tampered blood vial, lack of any evidence about where the crime actually took place etc.
I suspect we've not heard the last - a new piece of evidence and there'll now be a retrial.
However, I suspect the documentary was pretty skewed towards the defence and focussed solely on the evidence that was well defended. There didn't seem to be any motive for the crime put forward and that doesn't seem right?
Possibly the main tragedy is Brendan, who I suspect is completely innocent.