A mysterious series of attacks on American diplomats in Havana has lawmakers calling for an investigation of the State Department’s response.

A bipartisan group of five House members asked Congress’s independent watchdog to begin the probe, with an emphasis on how the State Department responded to the incidents and is working to prevent future attacks. The request comes in the wake of Secretary of State Rex Tillerson’s decision to withdraw most American officials from Cuba and expel most of Raul Castro regime’s officials from the United States.

“We are interested in how the Department of State responded to and investigated these attacks,” Rep. Ileana Ros-Lehtinen, R-Fla., and Rep. Albio Sires, D-N.J., wrote in a Tuesday letter to the Government Accountability Office.

Ros-Lehtinen is a former chair of the House Foreign Affairs Committee. Sires is the top Democrat on the panel’s subcommittee for the Western Hemisphere, which has jurisdiction over the State Department’s Cuba policies. They were joined by Rep. Mario Diaz-Balart, R-Fla., Rep. Carlos Curbelo, R-Fla., and Rep. Alex Mooney, R-W.Va.

Their questions suggest dissatisfaction with the State Department’s public statements and congressional briefings on the attacks, which have caused hearing loss and other “cognitive issues” in 24 American officials.

“What was the timeline of events involving the attacks in Cuba and State’s response to the attacks and the medical needs of those affected?” the lawmakers wrote in a series of questions for the GAO to review. “To what extent did State follow its policies and procedures with respect to the attacks in Cuba? To what extent has State taken steps to identify lessons learned by reviewing the facts surrounding, and its response to the attacks?”

State Department officials say the attacks began in Nov. 2016, but weren’t immediately identified as such due to the nature of the symptoms. They sent two Cuban officials home in May in response to the incidents, though that wasn’t made public until August. In October, Tillerson’s team expelled another 15 Cuban officials and slashed U.S. operations in Havana.

But the lawmakers might want a more elaborate investigation. “Was an Accountability Review Board convened, as an independent panel, to help identify vulnerabilities in the Department of State’s security programs?” they wrote. “If not, why not?”