REVEALED: Fired State Department IG was probing Trump administration's potentially illegal Saudi arms sales
US President Donald Trump and Saudi Deputy Crown Prince and Defense Minister Mohammed bin Salman shake hands at the White House on March 14, 2017. Trump heads to Saudi Arabia this weekend on his first foreign trip since taking office (AFP Photo/NICHOLAS KAMM)

Former State Department Inspector General Steve Linick, who was fired by President Donald Trump abruptly last week, had launched a probe into potentially illegal arms sales to Saudi Arabia.

Two sources tell NBC News' Josh Lederman that "Linick was also investigating use of emergency declaration last year to sell arms to Saudis over objections of Congress" at the time he was fired.

Aides for lawmakers serving on the House Foreign Affairs Committee tell the Washington Post's Greg Sargent that the investigation into the Saudi arms sales has been "mostly" completed, although there's no time table for when the results would have been made public.

Additionally, the State Department has reportedly been briefed on Linick's conclusions, although there is no evidence that his investigation is directly tied to his firing last week.

“I have learned that there may be another reason for Mr. Linick’s firing,” Rep. Eliot Engel (D-NY) tells Sargent. "His office was investigating -- at my request -- Trump’s phony declaration of an emergency so he could send weapons to Saudi Arabia."

Bipartisan majorities in the House and Senate voted last year to block arms sales to the Saudi government, although Trump proceeded to sell $8 billion to the Saudis by invoking an emergency declaration under the Arms Export Control Act.