Three Belgian doctors are going on trial in Ghent accused of unlawfully poisoning a patient who had requested euthanasia.

The sisters of the woman, Tine Nys, who was 38 when she died on 27 April 2010, argue that her reason for seeking to end her life was because of a failed relationship, far short of the “serious and incurable disorder” as required under Belgian law.

The three doctors from East Flanders who are going on trial have not been named, but they include the doctor who carried out the lethal injection and Nys’s former doctor and a psychiatrist. If found guilty they could face long jail terms.

The 38-year-old had suffered a childhood of severe psychiatric problems but had not had psychiatric treatment for 15 years. She was given a diagnosis of autism two months before her death but had not yet received treatment for it, the sisters say.