Now four international captains have reported approaches in the past year - two resulted in charges and the others remain under live investigation. The two that resulted in charges are understood to relate to approaches (both rebuffed) to Pakistan's Sarfraz Ahmed and Zimbabwe's Graeme Cremer and were investigated last year by the ICC.
Marshall has warned that the corruptors are now targeting associate nations looking to set up their own fledgling Twenty20 leagues, believing they are easy pickings, with low-paid players ripe for corruption and board officials naive about how the bookies operate.
Twenty20 leagues have been staged in locations as far and wide as Russia and Thailand.
"Two international captains reported approaches and they are ongoing investigations," said Marshall.
"There have been lots of leagues emerge in recent months and the corruptors see these as vulnerable events. The corruptors will look to approach captains in any form of the game, as they have the most influence over matches.
"The matches we are looking at are tests, ODIs, international Twenty20s, domestic Twenty20 leagues, associate member competitions and private leagues.
"The approaches often go through intermediaries, sometimes ex-players who are good third parties."
Marshall confirmed there had been no reports of approaches for the ongoing England v India series.
The ICC has had success recently. Two officials in Zimbabwe have been charged.
One was convicted and banned for 20 years for approaching Cremer to fix a match, and another, Enock Ikope, who runs the domestic franchise the Mashonaland Eagles and sits on the Zimbabwe Cricket Board, has been charged and is suspended pending a tribunal.