The woman volunteered with the Vancouver Pride Festival, where $9,000 was stolen, and TaiwanFest, where $3,000 disappeared from volunteers.
Sgt. Randy Fincham says in both cases, the woman would have had access to the funds.
"Follow-up with both festivals has determined that the volunteer had provided false information about her name and all efforts to identify the woman, who is considered a person of interest at this point, have been exhausted," he said.
"The Vancouver police now need the public's help to identify the woman."
She is described as a white woman in her late 30s, about five feet four inches tall with a heavy build and dark, shoulder-length hair.
Anyone with information is asked to call the Vancouver Police Department.
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