MYSTERY ON THE HUDSON AIRING ON '20/20 SATURDAY,' APRIL 23 ON ABC

Angelika Graswald sits behind bars, accused of killing her fiancé, Vincent Viafore, while kayaking on New York's Hudson River last April. But was it really a horrifying crime, or was it a heartbreaking accident in a very cold river with treacherous tides and unforgiving currents? Elizabeth Vargas' report airs on "20/20 Saturday" on SATURDAY, APRIL 23 (10:00-11:00 p.m. EDT) on ABC. (OAD: 11/6/15)

Elizabeth Vargas questions the only living person who really knows what happened that night - Angelika Graswald - in what was her first broadcast interview from jail. Graswald tells Vargas why she is heard on the interrogation tape telling police, "I wanted him dead and now he's gone." Vargas' report also includes evidence in the case, including the interrogation video and 911 call, and interviews with Graswald's two close friends, and a kayak expert who takes "20/20" viewers back to the Hudson River where the mysterious tragedy occurred.

"20/20" is anchored by Elizabeth Vargas and David Muir. David Sloan is senior executive producer.