If someone is caught doping before the last competition, you can't be 100% sure that they were doping before that as well.
Otherwise, they don't find the doping itself, but rather the traces of its breakdown. Otherwise, they would find it in 100% of cases while it's still in the body.

В тихой однообразной жизни всегда так бывает: каждый отдельный день бесконечно долог, но месяцы и годы мчатся с непостижимой быстротой.
I wanted to offer you some flowers, but a crown would suit a princess like you much better
Смысл жизни в том, что жизнь на тебе не заканчивается