Brech will be extradited to the Netherlands, he said, but it is unclear how long that will take. His body was found the next day but his killer has never been identified.
Spanish police have arrested a man on suspicion of having murdered a child in the Netherlands 20 years ago.
Nicky Verstappen, who disappeared from a campsite in 1998.
As time ran out to catch the suspect, police earlier this year appealed to more than 20,000 men to donate DNA samples in a bid to close in on the perpetrator.
A former scout worker was arrested Sunday in Spain in connection with the 1998 murder of a Dutch boy who was murdered at summer camp in the Netherlands that led to one of the country's most extensive murder investigations, officials said.
Brech became the main suspect in the murder after the investigation asked 16,000 males aged 40 to 65 from Limburg, the area of the murder, to voluntarily submit to a DNA test.
Dutch investigators said the victim was arrested near the Spanish city of Barcelona "thanks to a witness who recognized him after seeing his picture in the media in recent days".
Trump promotes white nationalist propaganda about South Africa
Opponents say EWC is a threat to food security and the economy. "We must ensure ownership of land for all South Africans", he tweeted.
Nicky's mother Berthie Verstappen breaks down in a press conference.
Dutch detectives said the outdoor survival expert's DNA matched traces on the body and clothing of Nicky Verstappen, who was found dead on August 10, 1998 near a summer camp in the Dutch countryside from which he had gone missing the previous night.
When his family reported him as missing in April, Dutch and French police searched his cabin in France's mountainous eastern Vosges region, where he owns a chalet.
Now, an arrest in a case that has been major news in the Netherlands and that involved a massive DNA undertaking. A search of his property allowed detectives to find DNA traces, which they say link him to the killing of Verstappen.
After being reported missing by his family in April, police examined Brech's home and found he is a 100% match for the DNA found on the schoolboy.
A European-wide warrant for Brech's arrest was issued on June 12.
They found traces of DNA on his personal belongings which matched samples taken from the slain boy's clothes.