From teenage cyber-thug to Europe's most wanted

> His officers also used novel forensics techniques to extract Kivimäki's fingerprint from an otherwise anonymous picture he posted under an online pseudonym.

Pictures of fingers have fingerprints.

This guy was sloppy, arrogant and callous to the extreme. Didn't bother to do the work to hide is tracks if it required significant work. He blackmailed tens of thousands vulnerable people. Accidentally releases all their data at once because his script had a bug.

The company that stored that information was almost as bad. They made no attempt to protect health data. It was a low hanging fruit.