They quickly bagged all of the plants and got rid of the indoor lights an hour before the police arrived. The police had a warrant to search the premises. No plants or grow lights were visible. The occupants denied growing marijuana. With no visible evidence of the plants, the police decided to look for trace evidence of pollen. Marijuana plants are known to release large quantities of pollen. Although the occupants of the house had removed the plants, they did not eliminate all of the microscopic pollen that was left on the floor and tabletops.