Police are studying video surveillance tapes after the dismembered head of a pig was left on the front steps of the police brotherhood offices on Gilford Friday morning.

The pig's head was placed in the middle of a pentagram, a star-shaped occult symbol sometimes associated with Satanism. 

The drawing was traced with chalk outside the doors of the police union's office at 480 Gilford, near the corner of St. Joseph and St. Denis.

"You have taken them alive! We want them back alive! May ghosts haunt you forever," read a message in French also left at the scene.

Police are considering it a criminal threat and began an investigation.

Other occult symbols staged at the main entrance of the police brotherhood headquarters included a large wooden stick figure.

Police investigators couldn’t reveal the meaning of the note, but said they will be reviewing surveillance tapes.

"There are cameras in and surrounding the building, so we'll look at the images to see if we can recognize somebody," said Montreal police representative Ian Lafreniere. 

Lafreniere said that it's not impossible that the message was meant to coincide with an upcoming demonstration against police brutality.

"Is there a link between that and the protest next Sunday? We have no confirmation whatsoever. It'd be too easy to make a direct link. Unfortunately in the past, in the days before the protest, we have had a few events here and there but it's never possible to completely link them," said Lafreniere.

Lafreniere said that those participating in the anti-police brutality protest on Sunday should provide an itinerary so the demonstration could be declared legal. "At this moment, with no itinerary, it's impossible to let these people walk," he said.