Organizers of an annual event which brings awareness to the disturbing number of missing or murdered Aboriginal women are outraged by the theft of a promotional sign.

On October 4, people will gather on Stephen Avenue Mall to remember the lost lives of Native women who have disappeared or have been victims of homicide.

Members of the Awo Taan Healing Lodge, the ‘Sisters in Spirit’ organizers, spend a significant amount of time throughout the year designing two awareness banners and fundraising to have the signs made.

One of the two banners, measuring more than a metre tall and nine metres wide, was removed from a northwest pedestrian overpass near Market Mall on Sunday.

“It's huge, so whoever stole this banner carefully thought this out,” said Awo Taan Healing Lodge’s Josie Nepinak. “The banner was put up by a construction company who donated their time.”

Nepinak says the $450 sign was cabled to the bridge above Shaganappi Trail N.W.  and would require tools to cut it down.

‘Sisters in Spirit’ organizers fear the theft was based in prejudice.

“We see it as an act of racism against Aboriginal women,” said Nepinak, “against the ceremony that's involved with missing and murdered Aboriginal women.”

The group had the proper permits to hang the banner and have reported the theft to the Calgary Police Service. The CPS Hate Crimes Unit is investigating.

Since the 1980's, over 600 Aboriginal women and girls have gone missing or were murdered in Canada, 93 of which are Albertans. The Stephen Avenue event, the 9th annual Sisters in Spirit, will be a sacred ceremony to remember their lives.

Organizers say the stolen banner will be a rallying point at this year’s event.

“With the sign going missing it will just make us stronger as people,” said Samantha Green. “It will make us drum louder and sing louder, and put our message across as loud as we can.”

With files from CTV's Kevin Fleming