This is a lake in Finland where 3 campers were killed and a 4th one injured severly. The sole survivor has been in a psychiatric institute for these last 45 years (1960). The investigation was recently reopened and they found out that the fourth camper was acctaully the murderer. He may not be charged seeing how he is unfit to stand trial and has been technically incarserated for 44 years already.
The band Children of Bodom got their name simply from the lake. It's not the killer just the lake.