According to reports, the trial began with a minute of silence in memory of the victims, whose ages ranged from 34 to 96. "We will make every effort to seek the truth".
A German former nurse accused of killing 100 patients in his care admitted Tuesday to the murders on the opening day of his trial.
Hoegel appears to have followed a similar procedure each time, first injecting a medication that triggered cardiac arrest, and then stepping in to resuscitate them.
They believe he was motivated by vanity, wanting to show off his skills and that he also acted out of "boredom". Known as Dr Death, Shipman was sentenced to 15 life terms in 2000; he died in prison in 2004, after apparently committing suicide.
The murderer was first caught in 2005 when he injected the wrong drugs into a patent at the Delmenhorst hospital.
HÃ¶gel's murderous activity. Investigators say he may have killed even more but potential victims have been cremated.
He has been labelled as Germany's most prolific serial killer since the Second World War for his horrific abuse of power.
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"It is like a house with dark rooms - we want to bring light into the darkness", he said.
Hoegel had already been sentenced to life in prison after being charged with at least six murders and several more attempts. Prosecutors say - his motive was to impress colleagues because he attempted to revive his victims after poisoning them. Prisoners serving life sentences are usually considered for parole after 15 years.
Before taking the stand on Tuesday, Hoegel had only acknowledged around 30 murders, all of them committed in Delmenhorst.
The Oldenburg state court is conducting the trial at a courtroom set up in a conference centre, a venue chosen to accommodate a large number of co-defendants as well as public interest in the proceedings.
Christian Marbach, a spokesperson for relatives, said it was a scandal that he had been killing for so many years with impunity.
He said: "If the people responsible at the time, particularly at the Oldenburg clinic but also later in Delmenhorst, hadn't hesitated to alert authorities - for example police, prosecutors".