From the butchers to the hairdressers and from the playground to the pub, a tiny pit village has been gripped by a baffling mystery.

Detectives in County Durham have revealed that at least 13 meticulously prepared bundles of cash, totalling £26,000, had been left at random places in Blackhall Colliery since 2014.

The latest – a wad of 100 £20 notes – was discovered on Monday morning and was the fourth handed in to police this year.

The mystery has stumped detectives, who have carried out numerous interviews, interrogated the local bank and post office staff and even tested the cash for fingerprints, but the circumstances surrounding the money remain a riddle.

Speaking outside the village pub on Tuesday, hoping to crack the case on his day off work, DC John Forster said: “I am hoping this is some sort of purposeful benefactor who is showing some kindness towards the village. I would rather that than someone who is vulnerable in some way or that it was connected to criminality.”

Forster praised the honesty of the 13 people who had found the £2,000 bags and handed them in, adding that they had been found in a “very tight” geographical area in the centre of the village. “One lady who handed it in was shaking – I don’t think she had ever been in a police station before,” he said, adding that police had asked those who handed the money in to keep quiet in the hope that detectives would solve the case.

One theory is that the money could be the ill-gotten gains of a local drug dealer, although Forster said that did not tally with his knowledge of criminals being ultra-watchful with money.

Facebook Twitter Pinterest Doris Huntington: ‘It could be one of these secret millionaires who wants to do good for the people.’ Photograph: Richard Saker/The Observer

In Grace Hair and Beauty, along the high street where most of the cash has been found, the mystery behind the cash was all customers were talking about on Tuesday. “It could be one of these secret millionaires who wants to do good for the people,” said Doris Huntington, 88, as she got her nails done. “You think he would leave it where a certain kind of people could find it rather than random. It’s very honest they’ve handed it in. Money’s no good to me now anyway.”

Lorraine Hall, 43, said the village had been abuzz with rumours and theories since the news broke. “I think it’s somebody that’s trying to do something nice – maybe someone who’s lived in the village all their life and they haven’t got family. A mystery Blackhall Santa,” she said, after serving the lunchtime rush in the cafe.

But in the village community centre, the whispers began seven weeks ago when one of the coffee morning regulars said she knew someone who had chanced upon a bag of £20 notes. “I think it’s really weird,” said the manager, Alison Paterson, 52. “I watch too many movies and I wonder if it’s someone who’s got people coming after him and he’s got too much money.”

Paterson said she initially thought some of the money might have been stolen during a break-in at her community centre in September – but then realised the mystery deposits began in 2014. “It just feels like someone’s done it to create some interest. Maybe it’s going to turn into a good news story – a secret millionaire who’s dishing it out. I hope there’s a fairytale ending.”

Facebook Twitter Pinterest Gaynor Crute: ‘Everyone is talking about it.’ Photograph: Richard Saker/The Observer

Gaynor Crute, the chair of Monk Hesleden parish council, which includes Blackhall Colliery, said she had been scratching her head to think of any lottery winners or businesspeople with a local connection who might want to give back to the village, but was at a loss.

“It’s from the youngest to the oldest – everyone is talking about it. It’s all around the village. People have got their own little theories. It will be keeping people going for a while,” she said.

Crute said the area had suffered from hard times since the closure of its colliery in 1981 but that it was nice to know that people who maybe needed the money were instead handing it in. “It’s heartwarming to know your neighbours have got so much honesty and integrity,” she said, adding that her local running club would keep their eyes peeled on their next village jog.

Facebook Twitter Pinterest Alyson Anderson said the money might have been left by ‘Santa’s little elf’. Photograph: Richard Saker/The Observer

Like many former pit villages, Blackhall Colliery has struggled in recent times. Unemployment is nearly three times the national average, with one in 10 people out of work and almost one in three classed as “economically inactive”, mostly long-term sick or retired.

Putting up Christmas decorations in the village hall, Alyson Anderson, 30, said she hoped Blackhall would be known as “the most trustworthy village in the country” for the people who handed the money in. “It’s not a run-down area but nothing ever that good really happens around here. It might be someone trying to help – a Santa’s little elf. I hope it’s that.”