Whoever vandalized the roof of a Janesville non-profit’s building apparently knew what they were doing.

KANDU Industries Executive Director Kathy Hansen says their building on Adel Street in Janesville has been vacant since they moved into a new facility in Milton in July.

Hansen says a worker who was recently on the roof to do maintenance discovered that someone had made a number of deep cuts into the roofing membrane.

Hansen says the cuts were made in specific locations designed to cause maximum damage through flooding.

Hansen says the damage could have occurred any time from when the roof was installed in spring of 2024 until now.

Anyone with information is asked to contact the Janesville Police Department.