Maastricht police say they have made a major breakthrough in the hunt for the killer of an 11-year-old boy in 1998, and insiders say it may be connected to the mass dna testing in the region earlier this year.

A press conference is being held at midday to give more details but Dutch tv crime reporter Peter R de Vries said on Twitter that a ’20 year effort will be rewarded’.

Altogether more than 21,000 men in Limburg were asked to submit their DNA, making it the largest mass sampling exercise ever carried out in the Netherlands. Around 65% responded.

Officials said in January that the test may 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.