After asking the AFL and the Australian Sports Anti-Doping Authority to conduct an investigation into the matter on Tuesday, Evans told members the club believed it had been compliant with both bodies' rules and regulations.
In the letter, posted on the Essendon website, he wrote: "We believe that we have acted in a sensible and responsible way to ensure the club gets to the bottom of this matter as quickly as possible."
Evans said the club would not be providing a running commentary as the investigation runs its course.
