Dunedin City Council rubbish detectives have caught and fined more than 30 illegal rubbish-tossers in the past 12 months.
DCC solid waste manager Ian Featherston said illegally dumped trash was searched for clues to find who owned it.
He would not reveal the exact methods used to find rubbish - for the same reason the United States military did not divulge details of its defence systems, he said.
"Because people would use it against them."
He said first offenders who were not aware they were doing anything wrong would usually be warned by council officers, but others received a $100 fine.
"Some of them think they are using council services but are not using council bags. Some are throwing them [bags of rubbish] where they don't want them to be found."
He warned members of the public not to try being rubbish investigators themselves, because only warranted council officers could inspect rubbish left in public spaces.
"Any rubbish put out on the street becomes council property," Mr Featherston said.
Instead, people should ring the DCC if they found rubbish illegally dumped.
Fines can go as high as $4000 through the court system, but all of the 32 instant fines issued in Dunedin in the past 12 months have been for $100.
