A note of appreciation from Tom Llamas as he signs off at ABC : “I want to thank the incredible team that produces this broadcast and the force that is ABC News – risking their lives, sometimes working never-ending shifts and not stopping until your questions are answered.” | ABC World News Tonight with David Muir

New surveillance video released by the FBI has shed new light on the abduction of Nancy Guthrie, Savannah’s mother. NBC News’ Liz Kreutz on what the disturbing doorbell footage reveals about the masked subject. | NBC Nightly News with Tom Llamas

A Delta Air Lines flight departing Houston’s Hobby Airport was forced to return after a man attacked flight attendants and other passengers. NBC News’ Tom Costello reports. | NBC Nightly News with Tom Llamas

A 60-year-old sewer line break in Maryland has sent more than 240 million gallons of untreated wastewater into the Potomac River, igniting a political firestorm. NBC News’ Tom Costello reports. | NBC Nightly News with Tom Llamas