High-tech method of identifying terrorism suspects
Wearing a disguise does not prevent police identifying an offender, as the latest weapon in the fight against paramilitaries can unmask gunmen at the click of a button.
The technology which can identify suspects even if their faces are covered with balaclavas is increasingly being used.
Experts compare images of masked suspects with photographs of their faces uncovered.
They then map features from the disguised faces of those being investigated, comparing them to the dimensions and characteristics of those concealed.
Two men have been successfully convicted after the PSNI used cutting-edge facial-mapping technology to identify them.
In May 2013, Londonderry man Patrick John McDaid (43) was found to have managed a meeting in support of the IRA.
His trial heard evidence from experts in facial mapping that the masked man carrying the flag at the head of a march in the City Cemetery in Derry on Easter Sunday 2011 was McDaid, despite the fact that he was wearing a balaclava.
Tiernan Porter (21) was jailed last year for a paramilitary-style shooting in west Belfast. He was identified after police used facial mapping and social media to track him down.
Police recovered a firearm and were able to link it to the shooting. A mobile phone was then found to contain pictures of a masked man holding the gun. The serial number of the weapon was distinguishable from the pictures so facial mapping was then used to identify Porter.