A 74-year-old man from Castricum has been arrested in an investigation into the sale of so-called suicide powder and is thought to have had a role in at least four deaths.

The man may have sold the powder to more than 500 people online and ‘earned considerably’ from doing so, the public prosecution department said on Friday.

The investigation began after a suicide in Zeeland and a suspicious death in Breda. One of the two people had a package in their home which could be traced back to him, the department said. The man will be in court for a remand hearing on Friday.

The powder was first presented as a humane way of committing suicide by the Coöperatie Laatste Wil (CLW), a right-to-die campaign group in 2017.

The cooperative sold it via meetings at members’ homes but stopped this last year after several people were arrested, including the organisation’s chairman.

The powder, a preservative, is legally available in the Netherlands unless sold as a suicide aid.

Last July a man named as Alex S was arrested for his role in distributing the powder, which justice ministry officials say may have been involved 33 deaths.

And in October, psychologist Wim van Dijk told the Volkskrant newspaper he had given the  powder to more than 100 people. He said at the time he had gone public with his actions to stir up public debate.