In Teller v. Industrial Commission, 179 Ariz. 367, 369, 879 P.2d 375, 377 (App. 1994), the carrier issued a notice to a worker at an electronics assembly plant indicating that benefits paid in connection with the worker's asthma were terminated. Id. The notice was based on a "twenty-day letter" that stated the carrier's intent to terminate benefits in twenty days unless the claimant produced medical evidence to establish that her ongoing injury was caused by working conditions. Id. The Court held that the notice was void on its face because it was based on a letter that asserted, without supporting medical evidence, that the symptoms were no longer related to the industrial injury. Id. at 374, 879 P.2d at 382.