Yes it was. The players also admitted it themselves.
The physio that caught them told the club right away and Stewart Duff spoke to the players the next day where they admitted taking cocaine. The players were summoned to a formal hearing, before the whole story broke into the public domain, where they then denied taking drugs. This infuriated Saint Johnstone. They were then sacked for gross misconduct and breach of contract. This is when the story made it into the press.
Thomas and O'Boyle then contested their sackings and went from court to court (SFA, SPL and an employment tribunal) as they continuted to fight their sacking. One court actually found them guilty of taking drugs and O'Boyle dropped his case after this. Thomas however pressed on and was determined to claim in the region of ?90,000. In the end he was awarded ?3,000 because of certain legal loopholes in the system.
Both players have since been in the papers admitting they took drugs. Neither have shown any remorse and lied to Saint Johnstone to try and get themselves off the hook.