U.S. Olympic drug cops are walking the beat in Athens. NBC News got an exclusive look at just one of the more than 2,000 surprise drug tests this year ... complete with an escort to the bathroom.
"The overwhelming, vast majority of our athletes are drug-free and, they want to be exonerated through the process," says the U.S. Olympic Committee's Chief of Sport Jim Scherr.
But drug investigators say that process was tricked last year by the now-infamous BALCO lab in California. Two company officials were charged with distributing a strength-building steroid called THG.
"THG had never before been described or synthesized or published anywhere," says Dr. Don Catlin of the U.S. Olympic drug lab.
THG had come in under the radar, but when a test was devised, there was suddenly a long line of athletes testifying before the federal grand jury investigating BALCO. All of whom deny any illegal drug use.
A dozen drug cases, eight involving THG, have taken their toll on the U.S. team. Among the missing from Greece: world-record holding sprinter Tim Montgomery, charged with doping; also banned, runners Calvin Harrison and his brother Alvin. All deny the charges. Sprinter Kelli White accepted a two-year suspension.
"There is a very serious problem and it is a very sleazy thing because it is not a case of an occasional athlete taking a cold medicine or supplement by accident," says Dick Pound of the World Anti-Doping Agency.
Gold-medal sprinter Marion Jones has been a lightning rod in the drug scandal. She has not been charged, but was questioned by investigators about BALCO. She qualified to compete in Athens, but only in the long jump.
To keep the games clean, enforcement has come to the games, but you'd never know it's headquartered at a non-descript building behind the Olympic tennis courts.
There will be almost 4,000 tests looking for 300 banned substances. The wild card is human growth hormone. The drug cops say they have finally developed a test for it, but they will not tell cheaters if the hormone test has been perfected.
"I would rather have them faced with a very rather unpleasant surprise if they try to use it here," says Pound.
Most athletes, like cyclist Giddeon Massie, accept the testing.
"This is what I do. This is my life. This is my job," he says.
It's a job that may include a knock on the door.
These will be the most-tested Olympic Games, but because new substances are being discovered, NBC News has learned they'll be re-testing the samples from the medal winners in the Salt Lake City Games, two years ago.