The 15-metre tunnel for the planned bank heist probably took about two months of continuous digging and would have produced some 900 50-kilogram sacks of rubble, experts estimate.
Construction and excavation professionals told Times of Malta the tunnel leading to St Andrew’s HSBC branch would likely have been made using hand tools, such as a handpick and possibly an electric jackhammer.
This would not have made too much noise and the sound would have abated further the deeper they excavated into the tunnel.
The experts said that whoever was behind the excavation clearly had a background in structural engineering.
“The team that did this must have had someone who clearly knew what he was doing.
“The meticulous nature of the tunnel makes that very clear,” the experts said.
Residents and garage owners yesterday told this newspaper they had seen the diggers but never heard any digging sounds coming from the garage.
A tradesman who works from a neighbouring garage claimed they would often dig late into the evening. Preferring to remain anonymous, he said he had often noticed men leaving the scene past 10pm.
“I work very late and come back to my workshop at night.
“On a few occasions I had seen people leaving the garage and even out in the street near the entrance. But I never thought anything of it, why would I?”
Another garage owner said he had seen at least three men leaving the garage and smelt cigarette smoke around the garage on one occasion.
He said he shared a similar view to that seen from the diggers’ garage but was blown away by the audacious attempt.
The subterranean garage where police found the 15-metre-long tunnel is surrounded by about 50 rented garages.
The entrance to the tunnel was created by removing four courses of limestone slabs from the garage’s rear wall just below a street level window.
The window is positioned directly opposite the rear entrance of the St Andrew’s HSBC branch on the other side of Triq it-Tiben.
The attempted tunnel heist is the first instance of excavated robbery in Malta, according to crime historian Eddie Attard.
Mr Attard said similar methods had included the removal of stone slabs from the walls of jewellery stores in the mid-1950s and the demolition of facades of ration stores during World War II.
The new technique showed the increased skill and professionalism of modern day crooks, he said, adding that a bank vault would have proven trickier to crack than a jeweller’s.
“They might have dug the tunnel, but once they made their way to the vault they would have found two feet of reinforced concrete to get through.
“I doubt they would have gotten in,” he said.
“Maybe they had someone on the inside or they had another way in, but they weren’t going to dig through that.”
Mr Attard noted that recent crimes investigated by the police had shown an increase in criminals’ savvy.
“Over the past 10 years or so, crime in Malta has changed significantly.
“This is an example of just how different modern-day criminals are,” he said.
The garage, second from right, is part of a complex in St Andrew’s. Photo: Chris Sant Fournier