AMATRICE, Italy — Italian authorities are vowing 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.

They also called for efforts to ensure organized crime doesn’t infiltrate lucrative construction contracts to eventually rebuild much of the picturesque towns leveled in the disaster.

Meanwhile, rescue workers pressed on with the task of recovering bodies from the rubble, with hopes of finding any more survivors virtually vanished more than four full days after the powerful quake.

Over the past two days, they found six more bodies in the rubble of Hotel Roma in Amatrice, the medieval hill town in mountainous central Italy that bore the brunt of destruction and loss of life in the powerful quake. They recovered three and by late Sunday were still working to retrieve others that were hard to reach.

It wasn’t clear if those six were included in the overall 290 death toll given by authorities. 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.