The Transportation and Infrastructure Committee wrote to Boeing Chief Executive Officer Dennis Muilenburg to request the interviews, it said in a statement on Thursday.

“The committee believes certain employees may be able to shed light on issues central to the committee’s investigation, including information about the design, development and certification of the 737 Max,” the committee leaders said in the statement.

Boeing declined to answer an email asking whether it would allow its employees to be interviewed by the committee, but issued a statement criticizing the lawmakers’ release.

“We’re deeply disappointed the committee chose to release private correspondence given our extensive cooperation to date,” the plane maker said. “We will continue to be transparent and responsive to the committee.”