DALLAS -- A federal reconnaissance team of structural engineers gathered documents and interviewed officials to determine why the Dallas Cowboys' practice facility collapsed.
The engineers from the National Institute of Standards and Technology were in Irving this week talking to city officials and Cowboys representatives, among others, agency spokeswoman Gail Porter said late Thursday.
Everyone who was interviewed "has been cooperative," Porter said. She said the engineers finished their work Wednesday.
Cowboys spokesman Rich Dalrymple declined to comment on the federal inquiry.
Porter wouldn't comment whether the engineers also spoke with representatives of Summit Structures, the company that designed and built the tentlike facility, The Dallas Morning News reported.
Summit spokeswoman Laurey Peat said the company, based in Canada and Pennsylvania, "has never spoken with them and has received no call."
The collapse of the Cowboys' facility in heavy winds May 2 left 12 people injured, including a 33-year-old team staff member who is paralyzed from the waist down. The Occupational Safety and Health Administration has opened an investigation into the incident.
Porter said the engineers collected documents, but she did not go into specifics.
The newspaper said important city documents related to the facility are missing. The city of Irving says it did not retain building plans or any other documents showing which engineer certified the design.
State rules require that such records be kept for the life span of the building. An employee in the Irving inspections department said Tuesday the city has no building or engineering documents for structures built before 1995.
The Cowboys facility was built in 2003.
Irving real estate and development director Brenda McDonald said the city would not comment whether it was auditing such records or planning to revise current document-retention policies.
Irving officials have granted the Cowboys a demolition permit, but it was not clear Thursday evening whether cleanup had begun.