I'm not really up to speed specifically on EU laws but if a similar thing happened in the US, UK, Australia or NZ then I will pose that if the scenario wen't something like this ...
1. Ricco transfused
2. Blood was tainted and everything wen't wrong
3. Admitted to emergency with life threatening conditions
4. Ricco advised Dr what he had done and what went wrong.
5. Dr had a flip top head and blabbed all to the 5 o's
6. Police found no evidence at all in his residence.
(Feel free to correct anything in the story, I haven't had the time to follow it and what information is out there seems third hand.)
... then Ricco would walk (based on those loose facts), no doping charge, no criminal charges. Now if the story is slightly different and Rossi told the police (unlikely?) then the situation changes.
Doctors can generally only pass on patient information when they are complying with a court order, or, they believe their patient is about to cause grave injury to either themself or another person. Neither of those conditions existed.
France, Spain and Italy do have some odd laws regarding sports doping though so again, I'm only commenting based on the laws of countries I know about.
Edit: It's also worth adding that anything Ricco said whatsoever when in the condition he was in at the time i.e critical condition whether it was to Doctors, Police or anyone wouldn't generally able to be used to obtain a conviction.