Saudi Air Force member identified as gunman in Navy base shooting, White House rejects invitation to participate in House impeachment inquiry, and shocking video shows the death of migrant child in holding cell.Watch NBC Nightly News With Lester Holt at 6:30 p.m. ET 5:30 p.m. CT (or check your local listings).0:39 FBI Seaching For Saudi Gunman's Motive In Deadly Attack2:36 Two Deadly Attacks At U.S. Military Bases From Insider Threats4:06 Coast-To-Coast Storm Slamming U.S. With Snow And Heavy Rain4:27 White House Refuses To Participate In Impeachment Hearings6:22 Video Shows Teen Migrant Found Dead In Border Patrol Custody8:15 Inside Uber's Special Unit Investigating Sexual Assaults10:15 Watchdog's Warning On Outdated TSA Screening Equipment12:16 Amazon Blames Delivery Delays On Rush Of Orders, Bad Weather