The men deny conspiring to extort money for the painting's safe return
A court has heard how a gardener ran to challenge raiders making off with a masterpiece from a Scottish castle.
John Chrystie, 50, was weeding in the grounds of the Drumlanrig estate when he saw three men with Leonardo da Vinci's the Madonna of the Yarnwinder.
He set off after them until one of them produced a small axe to scare him off.
Five men are on trial in Edinburgh accused of trying to extort £4.25m for the painting's return. They are not charged with the 2003 robbery.
Mr Chrystie, who had worked for the Duke of Buccleuch in south west Scotland for 20 years, said he heard "banging and then alarm bells" on the day of the raid.
He told the High Court in Edinburgh he then saw a man wearing a white sombrero-type hat carrying something square.
The gardener said that from the colours he recognised it as the Leonardo da Vinci painting.
"When I realised what was happening I was going to have a go at one of them and he pulled an axe from his jacket, a small hand axe," he said.
"I veered off and just ran up the banking."
The jury at the trial was also told about the contents of a letter said to have come from from Lancashire-based Marshall Ronald.
The court heard that he wrote that he was acting for clients when he contacted a London firm of loss adjusters.
The letter stated: "We make it plain from the outset that we do not act for the thieves and have no knowledge as to the identity of the thieves."
The letter, sent by e-mail in August 2007, added: "Our concern is to negotiate the safe repatriation of the painting and negotiate the reward/finder's fee on behalf of our clients."
Loss adjuster Mark Dalrymple, boss of Tyler and Company of Adair Street, London, was told in the letter marked "strictly private and confidential" that "we believe as a legal team we can negotiate the successful and speedy return of this precious art work through an informal mediation-type process".
The trial heard that the e-mail letter was sent just days after Mr Ronald and his clients - Robert Graham and John Doyle - travelled to Glasgow to seek advice from Scottish corporate lawyers Calum Jones and David Boyce.
Jurors also heard a taped recording of a meeting involving the defendants in the extortion case.
The conversation revealed that Mr Graham and Mr Doyle "knew someone who knew someone" with access to the painting and they wanted to know if they could return it for a finder's reward.
Several times they are heard to seek reassurance that what they were contemplating was legal.
At one point, Mr Jones told them it could be done properly - it could be made just about "bomb-proof".
Marshall Ronald, 53, Robert Graham, 57, and John Doyle, 61, all from Lancashire, Calum Jones, 45, from Renfrewshire, and David Boyce, 63, from Lanarkshire, deny the charges against them.
They have pled not guilty to conspiring to extort £4.25m and an alternative charge of attempted extortion.
The offence is alleged to have taken place between July and October 2007.
The trial, before Lady Dorrian, continues.