Three armed robbers used a skylight under repair to gain entry to the museum from its roof, tied up the three guards on duty, and left on foot with 18 paintings, including a rare Rembrandt landscape and works by (or attributed to at the time) Jan Brueghel the Elder, Corot, Delacroix, Rubens, and Thomas Gainsborough, as well as some figurines and jewellery.

[7][8] Investigation of the crime proved difficult in the early going, since it occurred over the Labour Day holiday weekend, when many of the museum's officials including its director were vacationing far away from Montreal.

During the 1960s many of the museum's supporters among the wealthy Anglophone community in Montreal began to leave for Toronto due to increasing concerns over Quebec separatism.

[9] Terrorist acts by the Front de libération du Québec had led to martial law in the Montreal area two years earlier.

At the end of the 1950s, their political and economic domination of the city began to yield to its majority Francophone population, as Quebec separatism rose in the province.

These departures grew after the terrorist attacks of the Front de libération du Québec which led to a 1970 declaration of martial law in the city,[11][10] The Anglophone exodus deprived the museum of much of its traditional financial support.

In 1957, Bill Bantey, a former journalist who was appointed the museum's head of public relations, began reaching out for the first time in its history to Francophones.

He confessed to the theft and led police to a one-metre-deep (3.3-foot) sandpit near the village of L'Épiphanie, a short distance northeast of Montreal, where he had buried them wrapped in a tarpaulin with newspapers.

Thouin, who had killed a police officer attempting to apprehend him in a railroad warehouse, was reportedly terrified at the prospect of being returned to prison for a very long term.

On the night of Friday, September 1, four intoxicated men who had been refused entry to a downtown country-and-western bar retaliated by setting the club's steps afire; the ensuing blaze killed 37, the deadliest fire in the city in 45 years.

One of the men, who wore a pair of the pick-equipped boots used by utility-company workers to climb telephone poles, went up a tree next to the museum and got on to the roof.

[3] In the lecture hall, one robber stood guard with a .38-caliber Smith & Wesson handgun[9] while the other two removed paintings, jewellery and figurines from their displays and brought them to the museum's shipping department.

The thieves originally seemed to have planned to leave via the same skylight, but eventually concluded it would take too much time to put together a system of pulleys to get themselves and the stolen artwork out.

Collectively they estimated the value of the stolen work at US$2 million,[17] ($11.1 million in 2023[6]) All of the stolen paintings were by European artists from the 17th through 19th centuries: Most of the paintings taken were small works around a foot (31 cm) along their longest dimension; the three smallest (the Brueghels and Millet's La barrateuse) were less than 80 square inches (520 cm2), smaller than a standard letter-size piece of paper.

Among the former pieces were an 18th-century gold watch once owned by the wife of Jacques Viger, Montreal's first mayor; a 19th-century French blue enamel latch box set with diamonds and two 17th-century Spanish pendants.

At that year's Summer Olympics in Munich, Palestinian terrorists with the Black September Organization took 11 Israeli athletes hostage, eventually killing them along with a German police officer, the following day.

Those events were of particular interest in Montreal since the city was preparing to host the next Olympics, and as a result further news about the art theft got less priority in the media.

On August 30, another group of three thieves had broken into the summer home of Agnes Meldrum, wife of a Montreal moving-company owner, in Oka, roughly 30 kilometres (19 miles) west of the city.

Around Christmas 1972, a Montreal Gazette columnist reported that, in fact, most of the paintings had been delivered to the homes of wealthy collectors in Mount Royal, with a small portion diverted to the U.S.

[11] Mostly Francophone, they had often visited the museum but had frequently been asked to leave before its official closing time so that the mostly Anglophone staff could take their tea, which the students resented.

[17] As a result of these negotiations, approximately a month later the museum's insurance companies (primarily Lloyd's of London[21]) and the SPVM set up a sting operation.

The field had few nearby houses at the time and could easily have been monitored from some distance away, allowing the robbers to detect even the more subtle police presence necessary to support a sting.

From there the caller sent him to other phone booths elsewhere in the city, such as the Blue Bonnets race track, on St. Laurent Boulevard and at the Henri-Bourassa station on the Montreal Metro.

The records themselves had been transferred to microfilm, and by the late 2010s, with no one at the SPVM actively investigating the case to his knowledge, he believed the film was in danger of deteriorating.

A group of 20 paid out nearly $2 million; they in turn posted a $50,000 reward for the return of the paintings, which under the terms of the policies they legally owned as a result of paying the theft claim.

But like the Brueghel, it was later reattributed to the painter's assistants, after a conservationist determined that its red pigments had been mixed four decades after Rubens' death,[25] reducing its value and interest to museumgoers.

When the de Heems were being prepared for their inclusion in Masterpieces from Montreal, a Parisian art historian the museum contacted suggested that they were in fact the work of another Dutch master, Evert Collier.

[3] For example, Lacoursière attempted to allay his suspicions by falsely describing the rope lowered from the skylight as made of steel, but Smith quickly corrected him that it was nylon.

In 2007, during the filming of "Le Columbo de l'art" ("The Colombo of Art"), a Radio-Canada special on his career as an art-theft detective, Lacoursière visited Smith and offered him the million-dollar cheque on camera.

While he again denied any role in the theft himself, he claimed that professors and porters at the Université du Québec à Montréal, which the École des beaux-arts had merged with in 1969, were behind the robbery.