A former male nurse serving a life sentence for two murders in Germany, is suspected of having killed at least 24 more patients with lethal drug overdoses. Investigators plan to carry out exhumations until the end of May to examine remains of possible victims. The man, identified only as Niels H was convicted in February last year over two patients’ deaths at a clinic in Delmenhorst, north Germany.

In court, he admitted killing up to 30 patients with heart medication. The deaths took place between 2003 and 2005. If found guilty over the other deaths, Niels H would become one of Germany’s worst post-war serial killers.