“We suspect more than one perpetrator was involved,” said Mats Karlsson, deputy police chief in Malmö, at a press conference on Friday morning, but added that the investigation is still in its early stages.
It is the fourth attack in two months following a similar pattern – one woman attacked outside by more than one person, and police have called in a national group specializing in criminal profiling.
The group will look at if the attacks could be connected, however police do not necessarily suspect that they are. “We see no direct links, but we are not ruling anything out,” Karlsson told journalists.
“We need to treat these types of crimes with caution. It's a person who has been through something deeply traumatizing,” he added, saying a lot of resources have been allocated to the investigation.
The woman, who is over 18, was able to get home and called the police shortly before 1am. She was taken to hospital for further examination at around 3am and her physical injuries are described as minor.
Officers cordoned off a large area of the scene in the Högaholm area of southern Malmö and scoured the area for evidence overnight. They continued to question witnesses and go through CCTV on Friday.
Karlsson appealed to the public to contact police if they have any information and urged people to live their lives as usual and not avoid going outside, arguing that busy public areas deter would-be criminals.
“That in itself helps prevent crime,” he said.
Police have previously said about the three attacks in the city in November and mid-December that the victim and perpetrators are believed to have had some form of contact before the attack.
“The contact was vague but we can say that the reported crimes are not cases where the perpetrator waited for the victim in ambush,” Karlsson said in a statement published earlier this month.
In some of the other attacks police have secured traces of DNA, but have made no arrests.
Police have previously urged people not to spread rumours about the attacks. In one case social media rumours held that one girl who suffered minor physical injuries in a rape in mid-December also suffered burn injuries to her lower body. However, police said a medical examination showed no signs of burns.