Identification evidence was wrongly dealt with at the trial of a man jailed for an iron bar and pistol-butt attack on a family in their home in Lavey in 2012, the Court of Appeal heard on Tuesday.
Lawyers for Michael Mongan claimed there were flaws after a pensioner and her teenage grandson both picked him out as having battered them during a botched robbery.
Mongan, 24, is serving a 14-year prison sentence for assaults on Theresa Convery, Philip Convery - then aged 16 - and her bank manager son Martin Convery.
A jury at Derry Crown Court also found him guilty by a majority verdict of attempting to steal £10,000 and with driving while disqualified and without insurance.
The victims were attacked at their home on the Mayogall Road, in June 2012.
Two men had burst in armed with a gun and iron bar shouting: “Give us the money”.
According to the barrister Theresa Convery provided no details of Mongan’s facial features in her description of the man who beat her.
He insisted: “This was no fleeting glance case.
“This lady clearly could have got a very good view of this person who was unmasked.
“But in this case she did not identify accept in a qualified nature.”
Following submissions judgment was reserved in the appeal.