The Gilbert family is front and center in Netflix’s new docuseries, Gone Girls: The Long Island Serial Killer. After Mari Gilbert pushed authorities to investigate the disappearance of her daughter Shannan Gilbert in 2010, the search led officials to the bodies of several homicide victims in Long Island. Shannan’s remains weren’t located until December 2011, and investigators do not believe she was the victim of a serial killer. Years later, Shannan’s mother faced her own gruesome fate. Mari was murdered by her daughter Sarra on July 23, 2016. Sarra stabbed her mother to death and was charged with second-degree murder and fourth-degree possession of a weapon. After fatally stabbing Mari 227 times, Sarra, who is schizophrenic, bludgeoned her mother with a fire extinguisher. Another one of Mari’s daughters, Sherre, addressed Sarra’s mental illness struggles in a Facebook post after Mari’s death. “So as a lot of you may know,...