RIO DE JANEIRO — In the months and years before Brazil’s National Museum was consumed by fire on Sunday, federal prosecutors, researchers and even the museum’s own administration warned that neglect had turned the 200-year-old institution into a tinderbox.

On Tuesday, evidence of this disregard came to light even as workers sifted through what little is left of the 20-million-item collection. The devastation has come to symbolize what many Brazilians see as a nation in disrepair because of widespread corruption and a wholesale decline in government services.

“We knew that the fire one day was bound to happen,” said Marcelo Weksler, a curator of the mammals exhibit. “Everybody here knew that. It was our worst nightmare.”

A citizen’s complaint, filed with the federal prosecutor’s office in Rio de Janeiro by an architect on July 27, included photos and pointed to specific hazards like the use of flammable plastic on the roof, uncovered wires and other evidence of jury-rigged wiring.