In a high-tech approach to a decades-old policing tool, law enforcement officers in Wales arrested three members of a family-run drug ring using fingerprints seen in a photograph sent over WhatsApp. According to the BBC, last weekend’s drug conviction is the first to use use fingerprints from a cell phone photo in the country’s history.

The three arrests happened after police found a photo on the phone of someone else they had arrested that showed a man’s hand palm up and holding ecstacy tablets. The photo was sent to the police’s “scientific support unit,” which uploaded the image into its image database. However since only parts of two fingers were visible in the photo, it didn’t find a match with other fingerprint records in the database.

Still, the investigating officers were able to use other bits of information they had to link the photo with the drug dealer himself. Once they had apprehended the drug dealer the pieces of the fingerprints in the photo could be matched with the full fingerprint of the dealer.

According to Dave Thomas, an officer involved in the case, the arrests really drove home the importance of data stored on cell phones when investigating a crime.

"While the scale and quality of the photograph proved a challenge, the small bits were enough to prove he was the dealer," Thomas told the BBC. "It has now opened the floodgates and when there is part of a hand on a photograph, officers are sending them in."

Moreover, Thomas said he hopes to put technology to greater use such that the evidence found on cell phones can immediately be put to use to catch criminals.

“We want to be in a position where there is a burglary at 20:30, we can scan evidence and by 20:45 be waiting at the offender's front door and arrest them arriving home with the swag,” Thomas said. “That will work through remote transmission: Scanning evidence at the scene and sending it back quickly for a match.”

Although this drug arrest is a first for Wales, it’s not the first time that fingerprints in a photograph have been used to identify a criminal. In 2015, law enforcement officers arrested and convicted a child pornographer by using photos of his hands that appeared in the child porn that he was peddling.

Perhaps the main lesson here, however, is that if you’re going to do illegal shit, don’t post pictures of it online.