The main span of the a pedestrian bridge after it collapsed over several cars causing fatalities and injuries. (AP/AP)

The U.S. Department of Transportation’s inspector general will launch an audit covering the collapse of a pedestrian bridge at Florida International University that killed six people last week.

The audit was requested by two top federal officials in dueling notices that hint at the political sensitivities of the tragedy. The bridge fell hours after a meeting was held at the construction site to discuss a crack discovered in the 950-ton concrete-and-steel span and two days after a voice mail was left — and missed — about the cracking, which was not deemed a danger.

Inspector General Calvin L. Scovel III “expects to formally announce the review and begin audit work related to the FIU bridge collapse as soon as possible,” said a spokesman for the office, adding that the scope and objectives of the effort would be part of the forthcoming announcement.

Many questions have been raised about whether the various levels of government, including state and university officials, made sound decisions and exercised proper oversight in connection with the project.

Transportation Secretary Elaine Chao released a letter Tuesday calling on Scovel to look into whether Florida International’s Board of Trustees, which she referred to as the project’s owner, and others followed federal requirements for the project, which was largely funded by the federal government.

The Federal Highway Administration said $13.6 million in federal funds went to the bridge as part of the University City Prosperity Project, which also included other community improvements.

Chao, in a letter dated Monday, asked the inspector general to “initiate an audit to examine whether the project owner and the design-build team and contractors responsible for the design, planning, construction, installation, and testing of the FIU pedestrian bridge complied with all specifications and requirements applicable to this project” given the federal funding.

But Sen. Bill Nelson (D-Fla.) indicated that Chao’s scope for the audit was too narrow. In a Tuesday letter, Nelson said “there have been conflicting reports as to whether the U.S. Department of Transportation (DOT), the Florida Department of Transportation (FDOT) and local entities exercised the level of oversight and adherence to safety and inspection rules required by” a federal funding source known as Tiger grants.

Nelson said a “fulsome audit” is needed of the actions of “all parties” to the federal grant agreement. He noted that not only Florida International but also the state’s transportation agency and the federal Department of Transportation had responsibility for the project.

The bridge also used “innovative design and construction processes, which may have required an additional amount of oversight from the various parties,” Nelson said, referring to accelerated bridge construction procedures that allowed a pre-built span to be erected quickly.

Nelson, who has requested a broad set of project documents from Chao’s department, said the inspector general should “carefully review all internal communications between the parties to ensure that no efforts are being undertaken to impede a full and forthright audit or investigation of this matter or to cover up any waste, fraud or abuse involving” federal transportation funds.

A spokesman for the Florida transportation agency said it is performing an internal review and will also provide any information requested in other investigations.

Maydel Santana, a spokeswoman for Florida International, noted that the National Transportation Safety Board “is conducting a thorough investigation, and we are cooperating and assisting authorities fully in the effort to understand what happened. We will, of course, cooperate with the U.S. DOT as well.”