Niels Hoegel is already serving time for 2 murders

A German nurse who's already serving a life sentence for two murders has been charged with 97 more.

Niels Hoegel was jailed in 2015 for killing two patients, and the attempted murder of two others.

In those cases he gave them overdoses of several different heart medications, leading investigators to look into the deaths of hundreds more.

The allegations cover his time at two German hospitals between 1999 and 2005 - in Delmenhorst and Oldenburg.

It's thought he may be Germany's most prolific serial killer.