When one of the most successful female athletes of all time, Merlene Ottey, was forced to withdraw fromthe 1999 World Championships, it sent shock waves through the sport.
Ottey, holder of more individual medals than any other athlete, had tested positive for nandrolone - an organic anabolic steroid - in Switzerland some months earlier.
The case came to light just days before the Seville championships and proved to be the first of many similar failed tests.
The sprinter has since been cleared by the Jamaican Athletics Federation and the International Amateur Athletic Federation (IAAF).
For others, however, the wait goes on.
Ottey's case was a watershed as numerous top athletes all hit the headlines for the wrong reasons.
The 1992 Olympic 5000m champion Dieter Baumann, 1992 Olympic 100m champion Linford Christie, European 200m champion Dougie Walker as well as Britain's Mark Richardson and Gary Cadogan all failed tests. Again nandrolone was the culprit.
When athletes are tested for the steroid, scientists actually search for nandrolone's waste product, 19-norandrosterone.
If this is detected in urine it is regarded as proof that nandrolone has been present in the athlete's body.
For men, the limit is two nanograms of the waste-product per millimetre of urine. For women the limit rises to 5ng/ml.
How it got there
The testing procedure, as a result, holds no particular mystery. The problem, however, is that once detected, no-one can be sure how the substance arrived in the body.
A comprehensive, independent survey recently carried out by a team of British scientists identified four possible sources of nandrolone:
Clearly, the problem for the authorities comes in the third explanation - whether athletes knowingly took pills or other products containing the steroid.
The chief executive of UK Athletics, David Moorcroft summed up the problem when he conceded: "It's possible tests do indicate guilt.
"It is conceivable some of them are guilty, that all of them are guilty or that - possibly - none of them are."
It is certainly a delicate matter and, while research continues, the authorities can do little except ask the athletes concerned for an explanation.
British bobsleigher Lenny Paul, claimed his positive test was the result of eating too much spaghetti bolognese, while Baumann, who has since had his suspension lifted, maintained the substance was injected into his toothpaste by an unknown foe.
Christie, who was said to have more than 100 times the acceptable level of nandrolone in his system, said his samples had been repeatedly taken in and out of the fridge and even left in a car overnight.
He was cleared by UK Athletics of any wrongdoing, but must now wait for an IAAF arbitration panel to decide his future.
Cadogan and Walker were similarly referred, despite being cleared by UK Athletics, though the Scot is hoping to overrule that decision at a high court meeting in London next month.