The police and the justice ministry are hoping to use private genealogy DNA data banks in an effort to solve two cold cases, in what would be a Dutch legal first, the public prosecution department said on Monday.

In particular, police want to access DNA held by two American companies – GEDMatch and FamilyTreeDNA – which were set up to allow people to find out about relatives and ancestry but which are also being used to track down criminals or identify victims of crime.

These two were chosen because users have to agree that their DNA be used in criminal investigations – a key condition for the Dutch investigations.

Investigators have been accessing commercial DNA banks in the US since 2018 and, the prosecution department said, have make breakthroughs in 550 cold cases. Sweden has also used them to solve a 2004 double murder.

The two Dutch cases chosen for the pilot concern an unidentified victim of a violent crime while the other is focused on finding a perpetrator.

Asked why an American DNA data bank can help solve Dutch cases, forensic scientist Lex Meulenbroek said the DNA stored is wide ranging and can reveal very distant family relations.

‘These are Americans and many of them have European roots. (..) Chances are that you will find a distant relative or, with a bit of luck, a close relative,’ he told the NRC.

The DNA data banks are an investigative tool, police said, and and anything found via them will not serve as proof. Regular DNA testing will have to show if DNA found at the crime scene, for example, matches that of a suspect found via the DNA bank.

The pilot project will only go ahead if the judges give the green light.