Handwritten letter and envelope from Niels Hogel.

Niels Högel (born 30 December 1976) is a German serial killer and former nurse who was sentenced to life imprisonment, initially for the murders of six patients, and later convicted of a total of eighty-five murders. Estimates of Högel's alleged victim count have increased since his first conviction; as of 2020, he was believed to have claimed 300 victims over fifteen years, making him the most prolific serial killer in the history of peacetime Germany.