The move to permit use of genealogy in police investigations has its roots in a citizens’ petition [borgerforslag], a type of official petition that can be started by Danish citizens and which parliamentarians must discuss if it gains at least 50,000 signatures.

Such citizens’ proposals are commonly rejected once they get to parliament, but the genealogy proposal has progressed further with parliament adopting it on Tuesday.

For genealogy to become a tool available to police, Minister of Justice Peter Hummelgaard must now table a bill which would change the law to that effect. A parliamentary majority would then need to vote to adopt the bill.

“We must give the police the best resources to investigate the worst crimes. We owe that to the victims and their families,” the minister said in a statement.

“In other countries, genealogy has proven to be helpful in police investigation of serious crimes. We can learn from that in Denmark,” he said.

“I am therefore pleased that parliament has broadly backed these new resources today,” he said, adding that the Ministry of Justice “is now working with the National Police to look into the options for introducing genealogy as an investigative resource”.

Data from genealogy has been used to solve crimes in the United States as well in Sweden, where it helped solve a 16-year-old double murder case.

However, Swedish authorities later found that the techniques used were in breach of data protection laws, according to the Danish justice ministry.

Genealogy can be applied to criminal investigations by enabling police to search for DNA profiles on external databases.

This can help identify potential relatives to persons relevant in police investigations.

Only one party in parliament – the centre-left Social Liberals – voted against the proposal on Tuesday. Two left wing parties, the Red Green Alliance and Alternative, voted neither for nor against.