Police in Spain made history by identifying a pedophile by his hand alone.
Forensic experts used footage of the 57-year-old pedophile assaulting an 11-year-old girl to help them identify his hands.
Authorities say it is the first time they've used such a technique.
"This identification is a milestone, since it is the first time that it has been possible to identify the author of a crime by looking at samples of the back of the hand, opening up new possibilities in the scientific investigation of crimes," said police.
The pedophile has been charged with repeatedly abusing the child while her mother was out of the house.
Drugged, the child was often unaware of what was happening. Then one day, her mother grew suspicious.
After investigating further, officials found photographs of the naked girl sleeping as well as the back of the man's fingers.
"These were then compared in minute detail with the pictures found in the girl's home," said a spokesman.
Social media users were thrilled to hear the news.
"God bless science!" wrote one Daily Mail reader. "Saving some children a lot of pain."
"This is the good thing about the world's continuous obsession with photographing everything," added another. "[H]ope they keep advancing this technique so they can catch more of these dbags!"
While others also praised authorities, some wondered if it was wise to talk about this new breakthrough.
"It's great if they do put him away, but I wish they'd keep this secret to law enforcement alone," commented one. "Letting these animals know how they can be caught will only give them other methods to protect themselves from being caught in the future. The public doesn't need to know... just go get him!"
However, some were skeptical the new technique will be effective.
"All I can say is, good, if true," wrote one. "Sounds a little dicey though without DNA or something more."
"This seems a bit of a stretch," added another. "My husband is a wonderful person and a teacher but his thumbs look very similar."
It's not the first time police have caught a pedophile in an unusual way.
In 2009, police identified a 50-year-old man by the freckles on his hand, The Telegraph reports. The man had been taking photos of Thai girls being sexually abused.
"There were some quite striking blemishes and freckles on the hands in the photograph," said prosecutor Peter Zinner.