LONDON Anti-doping authorities at the 2012 Olympics lived up to their pre-Games promise to banish any athlete found to be taking performance-enhancing drugs, but no one is under any illusion that means London was a squeaky clean Games.
By the start of the last day of the Games on Sunday, a total of 11 athletes had been excluded after testing positive for banned drugs.
For the rest - including every medal winner and many more top contenders - the jury is out until 2020.
Urine and blood samples taken at London 2012 and tested by scientists at the high-tech anti-doping lab in Harlow, east of London, will be stored for up to eight years.
As American cyclist Tyler Hamilton, a 2004 time trial gold medallist, found out on Friday, cheats both past and present can be named, shamed and stripped of their titles even years later.
Those sent home before getting near a medal podium in London included U.S. judo competitor Nick Delpopolo, who tested positive for marijuana which he blamed on unwittingly eating a "hash brownie", Russian cyclist Victoria Baranova, and Colombian runner Diego Palomeque Echevarria, who both tested positive for testosterone.
Two athletes - Albanian weightlifter Hysen Pulaku and Greek high jumper Dimitris Chondrokoukis - were barred after traces of the anabolic steroid stanozolol were found in their urine.
For some, like 16-year-old Chinese swimming sensation Ye Shiwen, the glow of Olympic glory was dimmed by insinuations of cheating in a doping row that had no basis in fact.
And while new cases didn't crop up every day, the return of many former drug cheats to the Olympic stage after serving bans for previous offences meant the reality of doping in sport was never far from the Games.
WISH YOU WEREN'T HERE
Turkish runner Asli Cakir Alptekin, who served a two-year ban for doping from 2004, took gold in the women's 1,500 metres, while Russia's Tatyana Lysenko, who missed the 2008 Olympics because of a two-year doping ban, won the women's hammer.
Other high-profile time-served drugs cheats included American sprinter Justin Gatlin, who claimed bronze in the men's 100m, and Briton Dwain Chambers.
London 2012 chairman Sebastian Coe was unapologetic in saying he wished such athletes had been banned for more than two years and had been kept out of his Olympics.
"If you're asking would I rather they weren't there, the answer is 'of course,'" he told Reuters.
Experts say the liquid chromatography and mass spectrometry equipment used at the lab to screen samples for more than 240 banned substances in under 24 hours has provided the best anti-doping system officials could have hoped for.
A spokesman for the International Olympic Committee (IOC) said on Saturday, a day before the Games' closing ceremony, that there had been 4,686 anti-doping tests so far, of which 3,729 were on urine samples and 957 had analysed blood.
"I'm impressed with what they've done, but of course there's always the potential that we're not catching people," said Phil Watson, a sports and exercise scientist at Loughborough University.
Watson puts part of the success down to significant effort and focus by the World Anti Doping Agency (WADA) and UK Anti-Doping (UKAD) to send out a "very strong pre-Games message".
"They were very keen to say if you're coming to London then you're going to be tested, so prepare to be caught," he said.
This was designed to urge national anti-doping authorities to step up their own pre-competition testing regimes to catch people before they turned up at the London Games.
SOPHISTICATED DOPERS ALWAYS AHEAD
Watson, who has been to the drug testing lab in Harlow and knows the work of David Cowan, head of the Drug Control Centre at King's College London and the man leading the 2012 anti-doping scientists, praised the systems as "absolutely 100 percent state of the art".
"WADA and the anti-doping agencies are doing all they can," he said. "But there are always going to be people who are one step ahead. That's the reality. There's a lot of money to be made in producing medal winners. And some of the people helping athletes cheat are very sophisticated."
Andy Parkinson, UKAD's chief executive, said the emphasis had also been on quality over quantity in the testing programme.
Intelligence gathered from everyone from Olympic village cleaning staff to customs officials at Britain's border controls has helped authorities target drug testing before and during the Games at the right countries, sports and athletes.
Parkinson said this intelligence-led approach, which anti-doping authorities have sought to learn from law enforcement experts, has taken time to adopt but has paid off in London.
"What we've been able to do as an anti-doping movement is recognise this is a model that can work, that helps us process things in a more efficient way and that gives us better returns and better value for money for the programme," he told Reuters.
Yet he too was sceptical about any claim that London 2012 has been a squeaky clean Games.
"I've got no way of putting a figure on it, but there's no doubt in my mind that there'll be a number of people in the Games who have been doping," he said.
"I can't say who and I can't say how, but statistics demonstrate that if you get that many athletes together, then there will be some."
"The only people who can tell us, hand on heart, that they're clean are the athletes themselves."
(Additional reporting by Mitch Phillips, editing by Sonya Hepinstall and Mark Trevelyan)
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