Abbey Conner, 20, and her brother Austin, 22, were both found floating in the pool-side bar at an Iberostar hotel in Playa del Carmen. Abbey Conner died days later, but her brother recovered. Local police did not question the bartender or other witnesses before declaring it an accident, according to the father. Reports say the pair consumed allegedly "poisonous" alcohol.

Joining Nancy Grace today:Bill Conner - Victim's Father Gary Davidson - Partner, Diaz Reus international Law Firm & Alliance, www.diazreus.com, Twitter: @DRT_Alliance, Instagram: diazreustarg Dr. Bethany Marshall - Psychoanalyst, www.drbethanymarshall.com, New Netflix show: 'Bling Empire'  Joe Scott Morgan - Professor of Forensics Jacksonville State University, Author, "Blood Beneath My Feet" featured on "Poisonous Liaisons" on True Crime Network Raquel Rutledge - Reporter, Milwaukee Journal Sentinel