MEXICO CITY — The capture was worthy of an action thriller: elite Mexican troops rappelling from a helicopter onto the deck of a mysterious submarine.

The 33-foot vessel turned out to be crammed with parcels believed to contain cocaine, possibly tons. Its disheveled crew of four emerged in stocking feet and baggy shorts, saying they had shipped out from Colombia a week earlier under threat of death.

Mexico's military confirmed Thursday that the men are Colombian but offered little new information on its capture of the mini-sub off the southern coast a day earlier.