The Miami-Dade County Fire and Rescue Department on Friday declared an end to its search for more human remains in the rubble of a Florida condominium complex that collapsed on June 24, killing at least 97 people.

Authorities said one victim was still believed to be unaccounted for.

The Miami-Dade Police Department will continue to sift through what is left of the debris pile for additional remains and personal effects, officials said in a statement.

The round-the-clock fire department operation at the beachfront site of the Champlain Towers South condo was demobilized four weeks and a day after the 40-year-old, 12-story structure gave way at about 1:30 am as residents slept.

“At this step in the recovery process it has become increasingly challenging to identify victims, and we are relying heavily on the work of the medical examiner’s office and the scientific, technical process of identifying human remains,”Miami-Dade Mayor Daniella Levine Cava said in a statement.

She hailed members of the search and recovery teams as “true superheroes.”

Nobody has been pulled alive from the ruins since the early hours after the collapse, and authorities formally gave up hope of finding any survivors on July 7.

County officials said in a statement that the confirmed death toll stands at 97 – consisting of 96 victims whose remains were recovered from the wreckage and one victim who died while hospitalised.

“We believe there is one victim still unaccounted for,” the statement said.

Investigators have yet to determine what caused the 136-unit building to crumble.

A 2018 engineering report found structural deficiencies that are now the focus of several inquiries, including a grand jury investigation.

The disaster has prompted officials across South Florida to study residential buildings for signs of poor construction or structural weaknesses.