Police are talking to householders and visiting schools in a bid to track down the culprit behind a spate of graffiti.
Officers are asking teachers if they recognise the tag, pictured, which has been spotted at least 10 times around Dacorum.
It has been seen in Hemel Hempstead’s town centre, Boxmoor, Chaulden, Warners End and Potten End.
PCSO Lee Jevon, who is investigating, said: “These thoughtless acts of graffiti are unacceptable and only succeed in defacing public areas meant for the community’s enjoyment.
“It’s very important that the person responsible is identified and I would appeal to anyone who knows anything to contact me on the non-emergency number 101.”