A doctor who slipped a sedative into a 74-year-old woman’s coffee before administering a lethal drug as members of her family held her down is to be the first medic to be prosecuted for breaching Dutch euthanasia laws.

A public prosecutor in The Hague said in a statement that the doctor could not have unambiguously come to the conclusion that the patient wanted to die.

It is the first prosecution since Dutch laws on euthanasia were drawn up in 2002 to allow a doctor to euthanise a patient if it could be shown they were experiencing unbearable suffering and making an informed choice to die.

The patient at the centre of the case was in a nursing home and suffered from severe dementia. Five years earlier, she signed a living will saying that she wanted euthanasia if she was competent in her mind at the time of its execution.

She had later given differing statements about her desire for euthanasia, prosecutors said, and her mental health had deteriorated by the time of her death.

On the day that she was killed, the doctor had a mid-morning coffee with the patient, her husband and her adult child, in what was described by the medic as a “cozy” atmosphere.

During this period, the doctor put a “secret” dose of a sedative into the patient’s drink, according to a medical complaints board report referenced by the prosecutor’s office in its statement.

After half an hour, the woman felt sleepy but she did not go to sleep. A second dose of the drug was administered via injection. The patient, although woozy, indicated her displeasure at the pain of the needle.

While she was asleep, the doctor attempted to administer a lethal dose of a different drug but the woman stirred from her sleep and stood up.

“The patient’s family then helped to restrain the patient and the doctor quickly administered the rest of the [drug],” according to a report of the incident.

The doctor under investigation, who was not named, had already been found by the medical complaints board to have breached official guidelines in her treatment of the patient on the day of her death and to have “overstepped the line”.

A statement from the public prosecutor said: “After extensive investigation, the public prosecutor also came to the conclusion that the nursing home doctor had not acted in accordance with the legal standards.

“The [prosecution service] considers it important that the court assesses whether the doctor was entitled to rely on the living will completed by the woman. In addition, the [prosecution service] reproaches the physician that she assumed that the woman still wanted to die without verifying this with the woman.

“Although the woman had regularly stated that she wanted to die, on other occasions she had said that she did not to want to die. In the opinion of the [prosecution service], the doctor should have checked with the woman whether she still had a death wish by discussing this with her.”

The case is due to be heard at the district court of The Hague. Two further criminal cases against doctors who have administered euthanasia have been dropped.