AMATRICE, Italy — Italian authorities are pledging to investigate whether negligence or fraud in adhering to building codes played a role in the high death toll in last week’s earthquake in Italy. [...] rescue workers pressed on with the task of recovering bodies from the rubble, with hopes of finding any more survivors virtually vanished four days after the powerful, magnitude 6.2 quake. The Civil Protection agency, which combines the figures it receives from different provinces affected by the quake, said the number is lower than the previous toll of 291 dead due to a correction in the numbers from the province of Rieti, where most of the victims died. The quake that struck before dawn Wednesday also injured nearly 400 people as it flattened three medieval towns near the rugged Apennines.