The doctor has been remanded in custody after he was interrogated by a Ljubljana investigating judge on Monday.

While the police refuse to reveal any official information citing protection of personal data, Dnevnik shows the doctor, Ivan Radan, being escorted handcuffed by plain clothes police officers.

The charges cap months of investigation triggered by revelations late last year that Radan had administered a deadly mix of potassium and morphine to a terminally ill patient.

Radan claimed he had only pretended to administer the drugs so as to trigger a debate about end-of-life treatment, but he was nevertheless fired by the UKC Ljubljana hospital.

An investigation into the suspected case dead-ended due to the absence of evidence as the patient was cremated, but it produced several leads that led police to suspect Radan committed dozens of mercy killings.

Dnevnik now reports that police not only charged Radan with murder, they also found that he was addicted to tranquillisers and had photographs of some of the victims on his computer.

Radan remains in custody for now and the investigating judge will decide whether he will be remanded until the prosecution produces an indictment.

While the case will now be processed by courts, Radan also faces having his doctor licence revoked.

The Medical Chamber is in the midst of investigating Radan's conduct and its chair, Andrej Možina, said the likelihood that malpractice will be established was "increasing". A decision is expected within three to four weeks.

UKC Ljubljana, which has come under heavy criticism for not detecting Radan's conduct earlier, said today it has reacted appropriately in firing Radan and the head of the vascular neurology department following an internal investigation in January.

The Health Ministry is meanwhile awaiting the findings of a special review of management and oversight at the department where the doctor worked, which is expected to be concluded by the end of June.

Minister Milojka Kolar Celarc said that the ministry will take action based on the findings, including by involving law enforcement should the conclusions show that the relevant bodies did not do their job in preventing Radan's actions.

Expressing regret over the Radan case, the ministry said there was no reason for the public to lose faith in doctors because of what "we hope is an isolated case".