More than 200 trees in Malmö have been damaged since November.
In addition, several buns with pieces of glass have been placed out in parks, which scares dog owners in the city.
The police have enlisted the help of their perpetrator profile group, but have not yet clarified who or who are the culprits.
- This is not something that only hurts trees, it also hurts the people of Malmö, says Nils Norling, spokesperson for the police in Malmö.
Several tips have come in, but the mystery is still unsolved.
- The crucial piece of the puzzle where someone has seen who it is is missing, says Nils Norling.
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