According to the prosecution, Péchier contaminated infusion bags with potassium, local anaesthetics, adrenaline and heparin in order to induce cardiac arrest or haemorrhage in patients treated by colleagues.
A court in eastern France sentenced a former anaesthetist to life imprisonment on Thursday after he was found guilty of poisoning 30 patients, 12 of them fatally.
The verdict against 53-year-old Frédéric Péchier came after 15 weeks of hearings, and the court had been deliberating the sentence since Monday.
Sentencing took three days as the court had to rule individually on each of the 30 cases of poisoning, which saw 12 people die and 18 others survive.
The acts were committed between 2008 and 2017 in two private clinics in Besançon, on patients aged between four and 89.
According to the prosecution, Péchier contaminated infusion bags with potassium, local anaesthetics, adrenaline and heparin to induce cardiac arrest or haemorrhage in patients treated by colleagues.
After refuting this theory during an investigation that was launched in 2017, Péchier finally admitted at the start of the trial that a poisoner had indeed been active in one of the two private clinics where he worked, but maintained it had not been him.
Péchier reportedly showed little emotion during cross-examination but broke down on 5 December when speaking about his 2021 suicide attempt.
"That's the way he is, Frédéric Péchier is someone who has always been in control, he doesn't like to show his emotions," his defence lawyer Randall Schwerdorffer said.
The anaesthetist "had underestimated the difficulty of this trial; he was convinced that the jurors would very quickly be convinced of his innocence," Schwerdorffer added.
Péchier's lawyer said he was convinced of his client's innocence and confirmed he would appeal against the sentence.