Mayor Romeo Dungca said the searchers, equipped with a payloader and a backhoe, have already dug up a 200-square-meter area in the Pasig Potrero River in Barangay Cabetican here, to a depth of 15 feet.
Angelo "Ador" Mawanay, who has identified himself as a former civilian agent of the defunct Presidential Anti-Organized Crime Task Force (PAOCTF), claimed it was in the area where he saw the drum being dropped into a crevice in the anti-lahar megadike.
Bentain was abducted on Jan. 16, 1999, and Mawanay implicated former ranking PAOCTF officers in his killing.
The ISAFP has been coordinating with Dungca in the search for the so-called "Bentain drum" amid fears that diggings might make the megadike unstable.
Dungca, however, said the material dug up from the megadike has been put back.
The mayor, however, doubts whether the drum could still be found. "I don’t think such a drum could have been washed farther downstream if it was really dropped into a crevice in the megadike," he said.
Earlier, Senior Superintendent Reynaldo Berroya, Central Luzon police director, said the drum could probably have been carted away after Mawanay first made his exposé.