Police in Wales found the photo on the messaging app of another person's phone, which showed a man holding ecstasy tablets with his hand palm up.
As reported by the BBC, although the parts of the two fingers in the picture did't match with fingerprints on record, they did lead to the discovery of other information that linked the snap to one of the dealers.
After the suspect was arrested, the fingerprints in the image were matched to the suspects, which led to 11 convictions earlier this month.
It's thought these are the first in Wales to be based on fingerprints taken from a mobile phone photo.
Officer Dave Thomas said: "While the scale and quality of the photograph proved a challenge, the small bits were enough to prove he was the dealer.
"It has now opened the floodgates and when there is part of a hand on a photograph, officers are sending them in."
In March, meanwhile, WhatsApp's co-founder urged Facebook users to delete their accounts.
Brian Acton joined thousands of people in taking to Twitter with the hashtag "#DeleteFacebook" trending on the micro-blogging site, amid the investigation into Facebook's breach of data.
He wrote: "It is time. #deletefacebook (sic)"