A mass dna test in Limburg to find the killer of an 11-year boy almost 20 years ago  will start next month, local broadcaster 1Limburg said on Wednesday.

Officials plan to ask 15,000 men to take part in the programme on a voluntary basis in what 1Limburger says is the biggest dna screening ever held in the Netherlands.

The mass test should have been carried out last year but was delayed to wait for the introduction of cheaper and more efficient dna testing techniques.

Officials hope the test will allow them to identify a close relative of the killer of Nicky Verstappen and say it is the ‘last realistic chance’ to find the murderer. Nicky was taken from his tent while at summer camp in August 1998. His body was found the next day but his killer has never been identified.

A cold case team started re-investigating the murder five years ago and now new techniques have allowed scientists to identify dna found on Nicky’s body and clothes. In 2010, police exhumed the body of an 85-year-old man in connection with the murder, without result.

A mass dna test in 2012 led to the identification of a Friesland farmer who raped and murdered schoolgirl Marianne Vaatstra in 1999.

And at the end of last year, police have arrested a man in connection with the rape and murder of a young woman 25 years ago after taking DNA samples from more than 100 men of Turkish origin in the Zaandam area. The suspect is one of the two men who refused to submit to the voluntary testing. He was traced after a relative was found to be a partial match.