Detectives believe 46-year-old Ryan Purdy, who also goes by Tracy Byers, approached several people in the park in December, flashed a badge and then took cash and credit cards from the victims.
One victim told investigators that the man said he was an undercover officer and that he and his partner were conducting an undercover operation inside Volunteer Park. The victim believed the man and allowed him to remove his wallet and look at his driver's license.
While the robber looked at the victim's license, he told the victim to stay away from Woodland Park and the Arboretum as well due to ongoing police activity.
The victim did not realize until the next day at work that one of his credit cards was missing from his wallet and his bank made several calls informing him of possible fraudulent activity.
Anyone with information about Purdy is asked to call the Seattle Police Department's robbery unit at 206-684-5535.