The pattern for this fly came from the fine book by Dick Stewart and Farrow Allen, Flies for Steelhead. They write that this fly was originally tied by Mike Kennedy in sizes 8 and 10 for the run of Rogue River half-pounders. In was later popularized in larger sizes on the North Umpqua by Ed Harzel.
Note: Marty Sherman, editor for Flyfishing Magazine, who originally submitted this fly for Stewart & Allen wrote that Stewart & Allen made a mistake when they listed this pattern with a purple hackle in their book. Mr. Sherman informed me that the hackle should be claret.
"I submitted the fly when the book was published and have samples of the fly tied by Ed Hartzell. Unfortunately when Mike Kennedy passed away we could find no samples of the Tranquilizer in the flies he left."