As noted before, Rey Mysterio tested positive for amphetamines back on February 13th but wasn't suspended until April 26th. He is currently serving a 60 days suspension. At the time Rey was told of his failure, he was told to submit all of the different medications that he was taking since he said he had no idea why he would have tested positive. WWE would have had their doctors evaluate the medications to see if there was a legitimate reason for the amphetamines.
The belief now is that a dietary supplement he was taking to lose weight could have contained a small amount of amphetamines.
Shortly after the drug test in February in San Diego, there was talk within WWE of frustration with him to the point it was said he would not be getting any kind of push upon returning. People were told in early March not to waste time coming up with angles or storylines for his return but no reasons were given. A very small number of people in the company would have known about the failure from February 13th until April 26th as doctors evaluated the case.
Mysterio, who is currently signed to a long-term contract with WWE, won't be eligible to return until June 25th. Since he was not working on the road, the two month suspension would likely cost him around $166,667 in salary.