Image 1 of 5 One of the blood bags from Fuentes' clinic (Image credit: AFP) Image 2 of 5 Eufemiano Fuentes was at the center of Operacion Puerto (Image credit: AFP Photo) Image 3 of 5 Alejandro Valverde (Movistar) in the points jersey (Image credit: Tim de Waele/TDWSport.com) Image 4 of 5 Ivan Basso and Floyd Landis at Criterium International in 2006. (Image credit: Getty Images) Image 5 of 5 Michele Scarponi answers a question at the Astana press conference. (Image credit: Tim de Waele/TDWSport.com)

The World Anti-Doping Agency has identified the athletes who more than ten years ago participated in a blood doping and performance-enhancing drug ring run by Eufemiano Fuentes, but are now looking to its legal team to determine if the Operacion Puerto information can be made public without WADA being sued, according to former WADA director general David Howman.

Howman spoke with the Spanish news outlet AS while attending the Congreso Deporte, Dopaje y Sociedad (Congress on Sport, Doping and Society) symposium in Madrid, not far from where the Guardia Civil uncovered the Fuentes clinic in 2006.

WADA received the evidence from the decade-old Operacion Puerto case after winning an appeal last June in the Madrid Court of Appeals to prevent the 211 blood bags from being destroyed. The evidence was tested in the WADA-accredited laboratory on Lausanne, Switzerland, but the results have not yet been released because of the legal concerns.

The statute of limitations for sporting sanctions under the WADA code expired in 2014.

"It is not an easy process. Operation Puerto has caused WADA and clean athletes a lot of frustration," Howman said according to AS.com. "Unfortunately, we continue without a clear outcome for 100% of its scope, and we also continue to debate with the lawyers about the list of those involved.

"So many people all over the world want to know the name of those involved. However, there are legal problems to deal with. Now it is too late, since the statute of limitations has expired, there is no possibility of punishment and it requires study and caution."

Howman agreed that the case needs to proceed to a final conclusion, whatever that might be.

"We will see how it is resolved. Operation Puerto needs to be closed, to know what there was inside it, to avoid it happening again in the future. It is evident that this saga of more than a decade is not going to produce an ideal outcome, but it is not in my hands. I respect the decisions of the judges, of WADA, and of the involved parties, although it is difficult to accept them."

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It is suspected that the blood bags belonged to some 36 athletes, not all of whom were cyclists. But the only athletes to so far have been identified as customers of Fuentes have been cyclists - Alejandro Valverde was linked to blood bags that contained traces of EPO through DNA testing, and served a ban. Ivan Basso was also banned after admitting to banking blood with Fuentes. Michele Scarponi served his ban for admitting to being involved, while Jan Ullrich was the subject of a determined effort by German anti-doping authorities, who linked his DNA to Puerto evidence.

But since then, the case has dragged on in the courts, with various judges ruling for or against providing the evidence to anti-doping authorities. At the time the clinic was raided and evidence collected, doping was not a criminal offence in Spain.

Eufemiano Fuentes was found guilty of endangering public health and given a one-year suspended sentence in 2013.