By Peter Szekely
(Reuters) -The death toll in the collapse of a Miami-area condominium rose to 90 on Sunday from 86, as crews continued their grim search for human remains in the building's wreckage, Miami-Dade County Mayor Daniella Levine Cava said.
Another 31 people were still "potentially unaccounted for," Levine Cava said at a briefing.
While many are feared dead in the concrete and steel rubble of the 12-story oceanfront building in Surfside that partially collapsed in the early morning hours of June 24, some of the missing have been discovered through detective work, she said.
The "unaccounted for" list shrank by 12 from Saturday, even as only four additional bodies were discovered.
"Our detectives are continuing to make progress in their audit and their diligent efforts of researching, verifying all reports on the unaccounted list and working with the families to open missing person police reports," Levine Cava said.
With no survivors rescued from the ruins since the first few hours after the collapse, officials last week declared that their search effort had switched from rescue to recovery.
Working around the clock with only a few safety-related pauses, Levine Cava said, workers have removed 14 million pounds (6,350 tonnes) of concrete and debris from the site.
The debris pile, which once stood four to five stories high, has been reduced to below-ground level in some spots where workers are seeing cars in the underground parking garage, Surfside Mayor Charles Burkett said.
As search teams sift gingerly through the wreckage, they have kept an eye out for personal items that are being cataloged and returned to victims' families, Burkett said.
"The work is still so delicate that we've even found unbroken wine bottles in the rubble and recovered them," he added.
Investigators have not determined what caused part of the 40-year-old Champlain Towers South to fall apart without warning. Attention has been focused on a 2018 engineering report that warned of structural deficiencies.
The local prosecutor, Katherine Fernandez Rundle, said last week that a sitting grand jury agreed to "look into how we can prevent such a disaster from occurring again" in coastal area buildings, with its findings to be presented in a report.
The work of a Dade County grand jury led to building code improvements after Hurricane Andrew devastated the area in 1992, she added.
The collapse has already prompted reviews of other buildings. Last week, residents of the nearby Crestview Towers condominium were told to leave after engineers found serious concrete and electrical problems. On Saturday, they were given 15 minutes to retrieve personal items.
Tests of Champlain Towers North, a nearby sister building of the doomed condominium, have found that its concrete is "at or beyond the levels that it should be," Burkett said.