Montgomery County has admonished the owner and builders of the Bethesda mall garage that partially collapsed during demolition last month — killing one worker and seriously injuring another — for lack of progress in restoring safe conditions at the site.

County officials also said they are still awaiting an analysis of why a 50,000-pound slab of concrete gave way in the garage at the Westfield Montgomery mall on May 23. But they said their immediate concern is safety at the fenced-off site, where work has been at a standstill since the accident.

“Work has now been stopped at the project for four weeks. Demolition is incomplete with severed [concrete supports], extra loads and other unsafe conditions of concern. This situation cannot continue,” Hadi Mansouri, chief of building construction for the county’s Department of Permitting Services, wrote in a June 20 letter to general contractor Whiting-Turner, structural engineer Vassil Draganov and Westfield LLC, the owner of the mall.

Progress was slowed over the last month by what Mansouri called “a significant problem” when Draganov, a principal at Robert Silman Associates, initially balked at preparing a report on the condition of the garage prior to the accident, the cause of the collapse and a plan for repair.

In a June 13 letter to Scott Titmas, vice president of Westfield LLC, Draganov said that such a report was “not within our . . . scope of responsibility.”

In his June 20 letter, Mansouri accused Draganov of attempting “to be absolved of all responsibility for all structural elements of the building through the duration of the project.”

Ultimately, Westfield hired an outside engineering consultant, KCE Structural Engineers, which helped compile a repair plan that was submitted to the county Thursday.

Draganov, Titmas and Whiting-Turner Vice President Chris Hoyson did not return phone messages this week.

The collapse occurred between the second and third levels of the garage, about 500 feet from Macy’s. The mall, on Democracy Boulevard just off Interstate 270, is expanding to include a new 16-screen movie theater.

Diane Schwartz-Jones, director of permitting services, said no work on the project would resume until the cause of the accident was fully understood.

The collapse killed Carroll Dexter Wills, 57, of Prince Frederick in Calvert County. Another worker was seriously injured but was not identified by authorities.

Yvonne Wills, the victim’s 83-year-old mother, said in an interview that Whiting-Turner has not offered an explanation.

“All I can say is that they paid for the funeral,” she said.