Last Wednesday the offices of the Norrländska Socialdemokraten (NSD) newspaper in Luleå were evacuated after the newspaper received a bomb threat via email.

The police were called to investigate, taking with them specially trained bomb-sniffing dogs, but by Wednesday evening investigators concluded the threat was a hoax.

But the story took a new twist on Monday when it was revealed that the IP-address associated with the threatening message is affiliated with police headquarters in Luleå.

“We’re now looking at all of our internet terminals, around 35 of them,” Norbotten police spokesperson Roger Jönsson told the TT news agency.

The police have several possible explanations: that the police’s network was hacked, that the message’s IP-address was wrong, or that the threat was sent by someone from within police headquarters.

“I’m not aware that the Swedish police (network) has been hacked, not in the last year, in any case. But it’s true, even the Pentagon has been hacked,” said Jönsson, referring to the headquarters of the US military.

The matter has been reported to the Swedish National Police-related Crimes Unit (Riksenheten för polismål). In addition, four investigators from the National Investigation Department (Rikskriminalen) are also working on the case.

Jönsson explained that police are now prioritising three things, including confirmation that the IP-address from the owners of the newspaper, Norrköpings Tidningar. From there, the IP-address must be connected to a computer, and then on to the person who used the computer.

Finally, police will look into whether or not their network has been hacked.

“As soon as we know something more we’ll be sure to go public with it,” said Jönsson, adding that some computers may have had several users.

According to Jönsson, the threat wasn’t sent in an actual email, but rather was delivered through on online tip form on the newspaper website.

However the threat, which arrived in the form of an email at 8.39am last Wednesday, was very clear, stating that the offices of the newspaper would be blown up at 2.35pm that afternoon, according to the newspaper.

Four hours after the threat was received, employees at NSD started to evacuate the building. But by 8.45pm police gave the all-clear.

“It feels unpleasant and unnecessary,” said NSD editor in chief Anders Ingvarsson at the time.