The charges against 33-year-old Thomas are with regard to his conduct while playing in three franchise-based tournaments: the Lanka Premier League (LPL), the Abu Dhabi T10 and the Caribbean Premier League (CPL).
In a media statement on Tuesday, the ICC said Thomas had breached the anti-corruption codes at all three tournaments and its anti-corruption unit had been authorised by all three boards in question - Sri Lanka Cricket (SLC), Emirates Cricket Board (ECB) and Cricket West Indies (CWI) - to conduct the investigation on their behalf. In a media statement, CWI said it would fully support the ACU investigation and that it was resolute about "denouncing corruption" in cricket.
The most serious charge against Thomas - of attempting to fix a match - is from the 2021 edition of the LPL when he played for Kandy Warriors. Incidentally, Thomas played just one game in that edition of the LPL.
Overall, Thomas faced four charges under the SLC anti-corruption code on his conduct in that tournament. The four charges are of "contriving or being party to an agreement to fix or attempt to fix, contrive or influence improperly the result, progress, conduct or other aspects of matches", "failing to disclose […] full details of an approach" to the ACU, "failing or refusing, without compelling justification, to cooperate" in an ACU investigation, and "obstructing or delaying" the investigation by "concealing, tampering with or destroying any documentation or other information".
Thomas also faced a single charge under the ECB code for failing to disclose details of an approach made to indulge in corrupt conduct during the 2021 edition of Abu Dhabi T10, when he was a part of the Pune Devils team.
The remaining two charges are from the last two editions of the CPL when he played for St Kitts & Nevis Patriots and Barbados Royals, respectively. One of the charges concerns, again, failing to disclose an approach. The second charge is about failing to report the "receipt of any gift, payment, hospitality or benefit (a) that he knew or should have known was made in order to procure a breach of the CPL Code, or (b) could have brought the player or the game of cricket into disrepute".
Thomas last played for West Indies in the day-night Adelaide Test against Australia in December 2022, his only appearance in the format. He has also turned out for West Indies in 21 ODIs and 12 T20Is since his international debut in 2009.