Karl Emil Malmelin (16 January 1872 – 26 February 1944[1]) was a Finnish farmworker and mass murderer.

[2][3] As an adult, Malmelin became a farmworker at the Simola croft in Klaukkala, a village in the southern part of the Nurmijärvi municipality.

Malmelin began dating Edla, the crofter's daughter,[4] but when she would not become his wife, he killed everyone on the croft with an axe on 10 May 1899.

The case was the subject of a broadside ballad, and Nurmijärvi parish became popularly known as Murhajärvi (which literally means "murder lake").

[5][8] Malmelin remains one of the worst axe murderers in Finnish history, along with Toivo Koljonen.