Cliff Stoll, the author of this piece, is best known for: https://en.wikipedia.org/wiki/The_Cuckoo%27s_Egg_(book)

"a first-person account of the hunt for a computer hacker who broke into a computer at the Lawrence Berkeley National Laboratory (LBNL)."

1989 - it started with trying to find the root cause of a 75 cent billing error on their shared computer system.

I highly recommend the book - I read it as a teen, and re-read it a couple years ago, it held up.