The trouble is cocaine can take 28+ days to leave your system, and would mean having act all odd if he was ever going to get tested. Just saying. He's better off with an opiate, heroin or a morphine amp would be ideal - completely out your system with 48-72 hours.
You can still trace Cocaine up to 3 months after use. If you test there hair, it will show up. Rio missed a drugs test by 1day, it was hardly the crime of the century, it probably made no difference to his results. The ban he got was a disgrace
Hair tests can actually go back further than 3 months these days And they'll show up everything, even if it's a short lasting drug like all the opiates.