A Europe-wide manhunt is under way for the suspected killer of an 11-year-old Dutch schoolboy on a campsite 20 years ago this month, after the largest DNA testing programme in the Netherlands’ history finally produced a 100% match.

In the latest twist to a cold case that has gripped the country since 1998, police in the southern city of Maastricht said on Thursday that more than 200 people had called in following an appeal for tips about the possible whereabouts of Jos Brech, 55, a former scout and playgroup worker.

“A lot of people are calling,” said police commissioner Ingrid Schäfer-Poels on Thursday. “We are now convinced the suspect has gone into hiding.”

Described as a survival specialist capable of enduring long periods alone in the wild, Brech was last known to be in the mountainous Vosges region of eastern France, where he has a cabin, and has been placed on Europol’s list of the continent’s most wanted fugitives.

The body of Nicky Verstappen, who had been sexually assaulted before he was killed, was found on 11 August 1998 in woodland a few kilometres from the youth camp in Limburg province, where he had been reported missing the previous day.

Despite an intensive and heavily publicised manhunt at the time, no arrest was ever made. But in May last year, exploiting new DNA analysis techniques, police launched an appeal to more than 20,000 men in the region to provide samples.

Nearly 15,000 – although not Brech – came forward, but none of the samples matched the profile assembled in 2008 from DNA recovered from Nicky’s body at the time of his death, detective Ferdinand Schellinkhout told Dutch media.

Brech, who in 1998 lived with his mother 13km (eight miles) from the campsite, was questioned three times during the inquiry – the first occasion just two days after the murder, when he was stopped by police while walking near the scene after midnight.

Facebook Twitter Pinterest The body of Nicky Verstappen was found on 11 August 1998 in woodland a few kilometres from the youth camp in Limburg province, where he had been reported missing the previous day. Photograph: Police Handout

He convinced investigators he was merely taking the late-night air, and while his name was recorded, he was never considered a suspect. “With the knowledge we have today, we clearly would have done things differently,” Schäfer-Poels conceded.

However, DNA provided by one of Brech’s relatives as part of the mass testing programme flagged him as a suspect, and he was formally identified last month from traces recovered from pyjamas he had left at his home which provided a perfect “one-on-one match”, chief prosecutor Jan Eland said.

Brech, who was briefly suspected but then cleared in a separate sex crime case in 1985, left the Netherlands in October last year. In February he told his family he was on an extended wilderness hiking trip in the Vosges, police said.

Relatives reported him missing in April, but an intensive search by both Dutch and French police since July has failed to find any trace.

A video released by the Dutch crimewatch TV show Opsporing Verzocht describes Brech as an experienced woodsman and survivalist who routinely uses natural hiding places, mountain huts and caves for shelter. He is also used to not communicating with the outside world for lengthy periods, police said.

“This is someone who often takes a long time to respond to emails, does not seek contact often and, because he has no mobile phone or social media accounts, is used to being unreachable for long periods,” police said.

The case has regularly returned to the public eye over the past two decades, with police exhuming the body of an 85-year-old man in 2010 as part of their investigation.

Nicky’s tearful mother, Berthie Verstappen, told a press conference of her relief that “after searching for 20 years, we finally have a name and a face”. She thanked a Dutch crime reporter, Peter De Vries, who frequently featured the case in his TV programme.

“Over all these years … the person who was most important to us is you,” she said. “If it hadn’t been for you, the investigation wouldn’t have moved forward for 19 years.”