Who said it was OK to transfer $400 million to Iran just as U.S. hostages were being released?

That question among many others is what U.S. Rep Mike Pompeo, R-Kan., wants to ask the U.S. Treasury Department, and he says he’s not going to back down until all is known.

“We all know it’s a ransom payment,” Pompeo told Fox News on Wednesday. “What we know now there is no way the money could have gotten to Tehran without the law being broken. … Sanctions were violated. Who instructed them to do it and on what authority.”

The Wall Street Journal reported Wednesday that U.S. officials held a cargo plane carrying the cash until the American detainees were freed.

“The report, which cited U.S. officials and others briefed on the operation, said an Iranian cargo plane was allowed to pick up the money in Geneva, Switzerland once a Swiss Air Force plane carrying the three detainees left Tehran last January,” Fox News said. “The White House has claimed that the $400 million payment in euros and Swiss francs was the first installment in a $1.7 billion settlement the Obama administration reached with Iran to resolve a failed 1979 arms deal dating from just before the Iranian Revolution.”

Pompeo said he wants “to make sure all the right people are held accountable for what took place here.”

“Someone had to sign the paperwork to transfer the money … someone had to approve this deal going down,” he said. “The administration tried to hide it.”

Pompeo said he wasn’t to “figure out if the law was broken and if so, by whom.”

“It does appears this was a conditional release,” Pompeo told Fox News. “These hostages weren’t going anywhere until that money arrived … That’s a ransom payment.

GOP leaders say they plan to hold hearings next month when members return from their summer recess.

The Obama administration has denied wrongdoing.