None can go back that far, the best can maybe pick stuff up that was used maybe a year to a year and a half ago ago (Deca being a big one), but the max time for testing is usually considered 3-4 months, most steroids and other drugs are far out of your system by that time. If an athlete picks his drugs right, and the standard blood or urine test is used, he could be on up to a week before the event and no one would be the wiser.
The oil based drugs are the worst, they tend to stick around the longest. They tend to disburse slower due to accumulating in fatty tissue, and the like.
