"Blue Rose" is the designation or code word for some FBI cases under Gordon Cole's leadership. Gordon Cole always sends his top Special Agents, such as Chester Desmond and Dale Cooper, to inspect and attempt to solve such cases.
The Blue Rose was referenced as Gordon Cole's 'Cousin Lil' was wearing one when briefing Special Agents Chester Desmond and Sam Stanley immediately prior to their trip to Deer Meadow, Washington to investigate Teresa Banks' murder. Special Agent Dale Cooper also referenced Teresa Banks' murder as being "one of Cole's Blue Rose cases" on the lake of Deer Meadow immediately after Special Agent Chester Desmond's mysterious disappearance. Although Chet Desmond and Dale Cooper had the chance to explain the Blue Rose to Sam Stanley, it was never explained to him.
Laura Palmer's murder investigation might be another example a Blue Rose because of the "curious linkage" to Teresa Banks' murder and the Twin Peaks Sheriff's Department's search for the Black Lodge, a continuation of the investigation into the paranormal and unexplained elements of both Teresa and Laura's murders. However, it is not clear if the designation was ever made for this case.
Behind the scenesEdit
Since there is no such thing as a blue rose in nature, the designation could represent cases which cannot be rationally or scientifically explained, the "impossible" cases. It could also be a reference to cases involving (or seemingly involving) UFOs, as part of "Project Blue Book" referred to by Major Garland Briggs and Windom Earle.