Currently a Chemical Operator, and while in the control room at my desk a fellow co-worker knocked over water on some paperwork.

Currently a Chemical Operator, and while in the control room at my desk a fellow co-worker knocked over water on some paperwork. I asked the employee and they became belligerant stating that they did not do it. Video footage was pulled and that employee was indeed responsible. Supervisor stated that I used an accusatory tone, and should pull this person aside and discuss. Last month another employee was asked to pull this person aside and speak on another matter. I feel that this person is given preferential treatment. Also now they are stating that I should have let them know immediately that paperwork was wet when I found it. Records get wet on the floor all of the time, and now they are making it an issue.Should I speak to this person or leave it alone? (small company)