The public prosecutor has called for eight years’ imprisonment, plus compulsory psychiatric treatment for Bart van U, the man accused of murdering the former health minister Els Borst and his sister, Loïs.

Bart van U, 40, told the court in Rotterdam on Tuesday that he was acting on ‘divine inspiration’ and had seen a vision telling him to kill the person responsible for euthanasia law.

Borst was found stabbed 41 times in her home in February 2014. Van U’s sister was stabbed to death in January 2015.

The prosecution is charging him with manslaughter, saying he is of partly unsound mind and acted on impulse. Experts from the Pieter Baan Centre, a psychiatric clinic, have said he has greatly diminished responsibility and requires compulsory treatment.

According to the Telegraaf, Van U’s defence lawyer has argued that Van U is ‘completely insane’ but claims the police and justice officers could have avoided the death of Loïs if they had not made mistakes.

Van U was arrested in Rotterdam in 2011 for illegally possessing weapons. He was charged for this but no DNA was taken. Had this been done, he could have been arrested faster after the killing of Els Borst which would have prevented the death of his sister, the defence argued.

He was caught by police only after the second murder in January 2015, after DNA tests led to him.

The Telegraaf reports that the Hoekstra commission, which has already researched what went wrong around the case of Bart van U, has said major mistakes were made by police, prosecutors and mental health professionals.

Sentencing is expected in 14 days.