Operación Puerto is an ongoing investigation (opened in 2006) by the Spanish police in to the activities of Doctor Eufemiano Fuentes, a sports doctor infamous for supplying professional athletes with performance enhancing drugs and associated training programs. Wikipedia provides a great summary.
Looking through the list of athletes implicated in the investigation, it does appear that the Spanish courts removed a number of Spanish athletes from the investigation (specifically from 2 Spanish cycling teams). Presumably there was more to this decision than an attempt by the Spanish police to protect Spanish athletes but I'm struggling to find an alternative explanation. Can anyone explain further?