Messages from around the world are helping pinpoint when three hand-carved Stations of the Cross were stolen from a unique chapel on Orkney, a gift to the islanders from one of the former Italian prisoners of war who converted two Nissen huts into a church that has become a major tourist attraction.

Police Scotland says information and photographs sent by recent visitors have helped narrow the time of the theft to between 9am on Wednesday 6 August and 5.40pm on Friday 8 August. Officers are still anxious to speak to anyone who visited between those dates.

Former PoW Dominico Chiocchetti, an artist from Moena, in northern Italy, returned several times after the war when the chapel needed repairs. He carved the 14 Stations of the Cross from mahogany and brought them as a gift in 1964. He died in 1999.

Three of the panels have now been stolen, a loss that John Muir, secretary of the local group that cares for the chapel, described as “devastating”. It is the second attack in three months.

The Italian Chapel on the tiny island of Lamb Holm was created in 1943-44 by Italian prisoners of war captured in north Africa. They were sent to Orkney to build causeways between the islands, as defensive barriers for ships moored in Scapa Flow. Confined to an island previously inhabited only by sheep, the prisoners plastered and painted, transforming the iron huts into a chapel that is now a listed building attracting about 100,000 visitors a year.

Chiocchetti, who had already created a statue of St George from scrap barbed wire and leftover concrete to decorate the square outside their huts, led the decoration of the chapel with craftsmen among his fellow prisoners who included a blacksmith, an electrician and a cement worker. Every trace of the original corrugated iron was plastered over and painted with ornate imitation brick and plasterwork. Prisoners gave up some of their cigarette money from the welfare fund to buy two gold curtains, shipped from a firm in Exeter, to frame the altar and the painting Chiocchetti regarded as his masterpiece, a Madonna and Child based on a little holy picture that he had carried in his pocket throughout the war. Even when the camp was disbanded and other prisoners were heading home, he stayed on for weeks to finish the work.

In May the Pope sent a blessing and his wish “that this chapel, built in time of war, may continue to be a sign of peace and reconciliation”, to a mass marking the chapel’s 70th anniversary. Days later a door was kicked in by vandals.