Police have been training to spot tattoos, books and even clothing that could indicate someone is a paedophile.
About 400 Durham officers were taught specialist skills developed by Texas police and Dr Joe Sullivan, an expert who has worked on the Madeleine McCann case.
They learnt about behavioural signs that could signal a potential child abuser and prompt the need for further questioning.
Dr Sullivan said he did not want to give more details to the public but that his knowledge had come from interviewing thousands of paedophiles.
"I have learned from that they have had to say, what are the key indicators that someone who may not have that level of knowledge may not pick up on.
"This training is about targeting frontline staff who are not working in the arena of child sexual exploitation."
It is the first time UK police have taken part in the Intervene to Protect a Child programme and it is hoped it will help them spot warning signs - even if the case is not originally flagged as child abuse.
PCSO Adam Grundy, 28, put his new skills to use just two weeks after the training, protecting a five-year-old girl.
He became concerned when he spotted a condom and a Viagra pill at the property of a man in his 80s during a routine call.
Mr Grundy said: "This guy was being very evasive with me when normally he would engage. He was very stand-offish and wanted me to leave.
"His personality had completely changed and that was something I referred back to in my training."
The training has also been completed by another 160 workers including teachers, fire officers and health workers.
"We are giving them the confidence to recognise, if people wear certain clothing, if people have certain tattoos, if people behave in a certain way, that might be an indication," said Durham's chief constable, Mike Barton.
"When you add these things together, that should give them the confidence to a frontline member of staff to do a bit more digging."
