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BARCELONA, Spain – In August 1998, 11-year-old Nicky Verstappen disappeared from his summer camp tent; his body was found the next day. Now, an arrest in a case that has been major news in the Netherlands and that involved a massive DNA undertaking.

The Guardian reports that as the 20th anniversary of Nicky’s death approached, Dutch officials in May 2017 put out a request: that roughly 20,000 men in the Limburg area where Nicky was killed submit their DNA that October as part of a mass testing program.

More than 14,000 did, reports the BBC. Jos Brech was not among them: The NL Times reports he left in October to hike in France’s Vosges mountains, reportedly telling his family he’d submit his DNA upon his return.

Except he didn’t return, and his family reported him missing in April. But the DNA trail still led to the 55-year-old survivalist and former scout leader.

DNA that Brech’s relatives provided showed the killer—who left his DNA on Nicky’s pajamas—was related to one of the donors, which helped authorities zero in on Brech.

They were able to recover a sample of his DNA from his home and confirmed it was a match, which earned him a spot on Europol’s most wanted list last week.

The Guardian reports police received a tip from a Dutch national who had seen the police photos and was visiting a commune-like community on the outskirts of Castellterçol, Spain, some 30 miles north of Barcelona, that Brech was there.

He was arrested Sunday and will be extradited to the Netherlands. Brech’s name was known to police: He was stopped two days after the murder while in the area and was questioned, but police deemed him no more than a passerby.

(Cops say this serial rapist was also sunk by family ties.)

This article originally appeared on Newser: 14K Men Gave Up Their DNA, and It Led to One Who Didn’t

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