Mari Gilbert's four daughters didn't have easy childhoods. Shannan, the oldest, was in foster care when middle sisters Sherre and Sarra were molested by Gilbert's boyfriend. Sarra went on to get an abortion at 14, drop out of school at 16, and have a baby with her drug dealer boyfriend in 2009. Shannan, meanwhile, became an escort, and disappeared on Long Island in 2010 in the middle of an escort call. Mari was consumed with the case, pushing cops to continue investigating her daughter's disappearance—and the search for Shannan ultimately led to the discovery of multiple bodies; the still-unsolved Long Island serial killer case is thought to have claimed as many as 16 victims. Then, in 2016, more than four years after Shannan's remains were found, Mari was killed—by Sarra, who stabbed her mother 227 times, possibly attempting to decapitate her, and beat her with a fire extinguisher before spraying it into her mouth in an attempt to drown her.
Sarra's life had continued to be difficult long past childhood, Robert Kolker writes in a long look at Mari Gilbert for the Cut. Sarra and her son's father, who served time on drug charges, would frequently split up and then reunite; Sarra ended up in a shelter for victims of domestic violence at least once. After Shannan's remains were found, Sarra suffered an apparent psychotic break and started suffering delusions; she had attacked her mother once before, claiming Mari was a demon. She was eventually diagnosed with paranoid schizophrenia and lost custody of her son to Mari in February 2016 after drowning her dog in the bathtub while her son was home. With the loss of her son, Sarra also lost her government assistance checks and ended up taking illegal drugs and skipping her antipsychotic drugs. By the end of July, Mari was dead. Read Kolker's full piece here; his book about the serial killings, Lost Girls, was recently turned into a Netflix film. (Read more Longform stories.)