How do Italian investigators try to prove that Michael Rasmussen has doped?

According to Italian laws, intake of performance-enhancing drugs is prohibited in this country.
Italy’s Anti-Narcotic Group is very strict and even aggressive in its activity to detect sportspersons that are suspected in administration of anabolic steroids or other banned drugs that possess performance-enhancing effects. Recently the investigation was connected with the Danish cyclist Michael Rasmussen.
Invisible microphones were set up in a certain pharmacy. The recordings don’t contain any information which could prove that Rasmussen had got anabolic steroids. But they contain a sound of an ampoule which is broken and thrown into a metal can. The investigators base their affirmations on this sound. They put effort to prove with the help of this sound that this famous cyclist doped. Michael Rasmussen notices that the investigators confirm that he was on the steroid therapy on that day. Don’t you find this conlusion strange?
The Danish cyclist noticed that he had purchased several medicines from the pharmacist Guido Nigreli for himself, his family and his pets. He said that he had got only legal preparations for therapeutic needs. The sportsman pointed out that he hadn’t purchased and taken any banned medications for athletic needs.
As it is known, Rasmussen’s sport history is not simple one. However this cyclist is a high level athlete and he is quite well-known, he wasn’t honest in any situation. This Danish athlete was removed from the 2007 Tour the France for lying. He was wearing the yellow jersey in the days before the race. He broke the rule of Tour the France and received a two-year suspension.