Whodunit with the paperknife in the library?

But after extensive investigation, a shortlist of suspects believed to be responsible for leaving three anonymous works of art linked to the writings of Ian Rankin at public institutions in Edinburgh has emerged.

Those fingered as possible culprits include a Danish paper artist, an Edinburgh College of Art (ECA) lecturer and an illustrator from the city.

Outsiders are a Banksy-style French street artist and a London-based miniaturist.

The tiny works of art have caused a sensation in the city since the first one appeared at the Scottish Poetry Library in March. Two weeks ago a sculpture was left in the National Library of Scotland depicting a coffin and a gramophone constructed out of pages of crimewriter Rankin's final Rebus novel Exit Music.

Another was left at the box office of the Edinburgh Filmhouse and showed a tiny version of the author himself in the cinema enjoying a pint of his favourite tipple, Deuchars, while tiny horses leapt out from the screen.

Earlier this year a third sculpture of a "poetree" was left at the Scottish Poetry Library, which included an extract from an Edwin Morgan poem. All three have included notes addressed to the institutions' Twitter addresses, commending them for being "in support of Libraries, Books, Words, Ideas … & All things *magic*."

Ever since, the race has been on to identify the artist, after Rankin himself denied any involvement and claimed to be flummoxed as to their origins. Veteran arts promoter Richard Demarco said he was sure the culprit would be someone with youth on their side.

"I'd be absolutely certain that it's bound to be a younger artist, and probably a recent graduate of one of the places where young artists work, either the Edinburgh College of Art or Telford," he said.

Demarco was enchanted by the sculptures. "It's a brilliant idea, and of course it tickles me because my whole inspiration has been Edinburgh - I applaud anything which is inspired by the reality of the city."

Anne Bevan, sculpture lecturer at ECA, had a few theories of her own.

"We would like to lay claim to it being one of our graduates, but quite often you would recognise your students' work and I would say it's not from a recent sculpture class. Then again it could be an illustration student," she said.

Bevan suggested that the sculptures bore some resemblance to the early works of London-based installation artist Slinkachu, whose semi-anonymous works are often left in public places and feature miniature figures.

She also suggested that they could be the work of undercover French street artist J?R, who has produced installations in locations as diverse as New York and Paris.Other names floated on the internet include Danish paper installation artist Peter Callesen, whose works also bear a similarity to the sculptures, and Jane Hyslop, an Edinburgh-based creator of artist books who lectures in the subject at ECA.

However, a growing number of art lovers believe the most likely culprit is Lucy Roscoe, an Edinburgh-based illustrator who graduated from ECA in 2008, did a masters there in 2010, and creates intricate works of art out of books including a Noah's Ark, a garden and even an entire street.

She has also worked for a number of book-related organisations, designed logos for the Wigtown Book Festival, and publishes her books under the moniker The Book Tree Press.

Peggy Hughes, communication and events officer at the Scottish Poetry Library, said Roscoe was one of the names they were looking at.

"It's certainly most like the work of Lucy Roscoe," she said. "But as far as we are aware she hasn't been in the library, and as far as we know she's not on Twitter."

Roscoe denied she was the artist yesterday but added intriguingly: "Then again you would be going against the spirit of the thing if you admitted it wouldn't you? If I had to come up with a name I'd start wondering about Rachel Hazell, the book artist, it sounds a bit like her sort of thing."

The Edinburgh Sculpture Workshop agreed that the culprit was likely to be someone who worked with artists' books. "We'd be very curious to find out because they're beautiful and really quite complex."

Others felt the answer to the mystery lay on social networking website Twitter.

"I really think it has to be someone who uses Twitter because all the sculptures are addressed to the places' Twitter names," said Hughes.

Some, however - including Rankin himself - have said they would prefer the identity of the artist to remain a mystery.

"I think it's more interesting if that's the case," said Jenny Leask of the Filmhouse, which is planning to put its sculpture on display. "We just want to let people see it. It's a beautiful thing."