Officer Derek White of the San Francisco Police Department suspects that the three skateboarders using the park fountain as a practice area are doing so in violation of city ordinance. Although he has asked them twice to leave the park, shortly after he leaves, they return. Encountering them for the third time, he elects to write them a summons but must first confirm that skateboarding in a public park is indeed a violation of municipal ordinance. Which of the following options is NOT available to him to confirm his belief?