The star Anglo-Italian - the three-times Champion Jockey who has 943 wins to his name, including 110 Group Ones - tested positive on September 16 at the end of the preparatory weekend at Longchamps.
He had competed in the Prix du Moulin de Longchamp, the Prix Gladiateur, the Prix Foy and the Prix Vermeille, amongst others, without a win.
A few weeks later, Dettori and Sheikh Mohammed, owner of the blue silks of Godolphin stables, announced the end of 18 fruitful years working together.
Pickings have been slim in 2012 for Dettori and there is a looming crisis. He has won only 51 times in 398 races and, above all, only three Group One wins. He has won an average of 10 per season for 10 years.
The Milan native has not had such a mediocre season since 2000, when his plane crashed between Newmarket and Goodwood and brought him within a hair’s breadth of death.
France Galop, which carried out the test on Dettori, is yet to announce the type of substance found in the jockey's urine, although it is reported to have been cocaine.
Dettori has history with the drug. In 1993, he was arrested leaving Wembley Stadium after the League Cup final between Arsenal and Sheffield Wednesday in possession of cocaine. At the time, the worthy successor to Lester Piggott in the affections of British fans escaped with a warning for his transgression.
After more than 14,000 races in 14 countries, the 41-year-old, whose retirement is rumoured to be imminent, could suffer a more severe punishment, which would usher his career towards an end little-worthy of his performances.