Sen. Markwayne Mullin (R-Okla.) has privately hinted to colleagues that he was involved in dangerous private security work in Middle East war zones before running for Congress in 2012, according to three people who have heard him discuss it.
Why it matters: It's a mystery likely to come up Wednesday at his Senate confirmation hearing, where he will face colleagues as President Trump's nominee to replace Kristi Noem as Homeland Security secretary.
