On Wednesday, a former nurse facing accusations of killing 100 patients at two northern Germany hospitals apologized for his “terrible deeds”.

According to the Deutsche Presse-Agentur or DPA news agency, the accused addressed the relatives of his victims. In a final statement to the Oldenburg regional court, Niels Hoegel, 42, said:

“To each and every one of you, I sincerely apologize for all that I have done.”

Hoegel’s lawyers argued that he should be acquitted from 31 of the 100 counts of murder charged against him. His attorneys suggested that those cases did not have incriminating evidence against their client.

One of his defense attorneys, Ulrike Baumann, told the court “Neither we nor Mr. Hoegel deny that he is the perpetrator in many cases.” According to Baumann, Hoegel “can only be convicted for crimes he committed and not for crimes he could have committed.”

Hoegel is believed to be responsible for the largest string of post-ward serial killings in Germany. The total deaths took place in an Oldenburg hospital from 1999 to 2002 and in a Delmenhorst Hospital between 2003 to 2005.

In 2015, Hoegel was convicted for two counts of murders and two counts of attempted murders. During his first trial, the former nurse admitted to intentionally bringing about cardiac crises in an estimate of 90 patients of Delmenhorst. Hoegel proceeded to say he enjoyed the feeling of being able to resuscitate his victims. He later admitted to investigators of murdering patients in Oldenburg.

Authorities had to exhume the bodies of former patients to investigate the hundreds of deaths.