Professor Dame Sue Black

Professor Black said that suspects can be identified by their penises alone and that it is the practice among many to upload such photos to websites and social media while hiding their faces.

The academic had asked RM Condor in Arbroath if Royal Marines would participate in setting up a prototype penis database to aid research but the idea was rejected by the Ministry of Defence.

She instead used a website which men had uploaded photos of their penises onto in order to record penile variation.

Currently, Professor Black is leading a £2 million research project into catching paedophiles using images of the backs of their hands to identify unique markings.

Police Scotland said they had not considered Professor Black’s suggestion but that they were receptive to new ideas.

Detective inspector Andy Mcwilliam, of the Cybercrime Unit, added: “We work closely with experts in all fields and are always interested to hear of any advances in technology which may help catch any criminal.”