Donald Peters, the chief executive of the West Indies Cricket board (WICB), confirmed the news and said action would be taken after advice from attorneys.
"They [the attorneys] are looking into the matter and will advise us on the course of action," Peters said. "WICB has a zero-tolerance policy on drugs and the matter could come up to the disciplinary committee. We are looking at a time frame of two weeks."
Peters said the board would take action, if any, on Marshall, as he was a centrally-contracted player, and would let the Leeward Islands handle Willett. Marshall was withdrawn from the Stanford squad on September 16.
The drug tests on the Stanford Superstars were carried out by the Caribbean RADO agency.