'20/20' EXAMINES MYSTERIOUS DEATH OF A WOMAN - RULED A SUICIDE BY POLICE - IN THE MIDST OF THE WRONGFUL DEATH CIVIL TRIAL AGAINST HER BOYFRIEND'S BROTHER

Hour Features Exclusive First Interview with Jonah Shacknai About the Deaths of His Girlfriend and Young Son Who Died Days Apart

'20/20' Airs on Friday, March 2 (10:01-11:00 p.m. EST), on ABC

Rebecca Zahau, girlfriend of pharmaceutical tycoon Jonah Shacknai, was found dead - hanging from the balcony of his Coronado, California, home, completely nude with her bare feet bound, hands tied behind her back and shirt stuffed in her mouth. Only two days before, Jonah's 6-year-old son, Max, had somehow fallen over a staircase banister in the same home and later died. Given the circumstances of her death, Rebecca's family remains skeptical of the police ruling that her death was a suicide and alleges that Adam Shacknai, Jonah's brother and the only other one staying at the property the night Rebecca died, is to blame and filed a wrongful death lawsuit against Adam. In the midst of her family's suit that went to trial this week, "20/20," with reporting by ABC News correspondent Sunny Hostin, features an exclusive first interview with Jonah about Rebecca and Max's deaths. "20/20" airs on Friday, March 2 (10:01-11:00 p.m. EST), on ABC.

The hour includes interviews with Dina Shacknai, Jonah's ex-wife and Max's mother; Mary Loehner, Rebecca's sister; Anne Bremner, attorney previously hired by Rebecca's family; Greg Hanchrow, senior New York City port captain who analyzes the knots found on the rope tied around Rebecca's hands; Keith Greer, attorney representing Rebecca's family in the wrongful death lawsuit; Itica Milanes, former KGTV San Diego anchor who reported on the deaths of Rebecca and Max extensively; and handwriting expert Lauren Mancebo who looks at the riddle left on the door of Rebecca's room, discovered after her death. The hour also features Herman Weisberg, a New York City private investigator, retained by "20/20" to do a deep dive into Rebecca's death. Weisberg explains his concerns about potential mistakes in the DNA testing and other inconsistencies with the evidence that he says need to be re-examined.

In the days after Max's fall, which police deemed accidental, parents Jonah and Dina attended to him in the hospital around the clock while Rebecca remained at Jonah's home. Adam, upon hearing the news, flew in from out of town and joined Rebecca on the property. During his stay, he claimed to have stumbled upon a shocking scene of Rebecca's body hanging from the balcony and called 9-1-1. Rebecca's family maintains that the circumstances surrounding her death do not add up and accuse Adam of being Rebecca's killer. Adam maintains his innocence, and his attorneys say there is no evidence that ties Adam to Rebecca's death. Authorities cleared Adam of any involvement in Rebecca's death.

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