Six years after the disappearance of her sister Shannan Gilbert led to the discovery of 10 sets of remains near Gilgo Beach, Sarra Gilbert has been indicted by a grand jury in upstate Ulster County on charges that she murdered her mother, Mari, in July at her apartment in Ellenville.

Gilbert, 27, was indicted Tuesday on a charge of second-degree murder, according to a copy of the indictment.

She has been held without bail at Ulster County jail since she was arrested on July 23 and charged with stabbing her mother to death. Ellenville police arrested Gilbert at the scene and said they recovered a 15-inch kitchen knife they believe was used in the attack.

Suffolk County attorney John Ray, who has long represented the Gilbert family as they sought answers in Shannan’s death, said Wednesday he visited his client last week and was unsure if she has undergone a psychiatric evaluation, as ordered days after her arrest, to determine whether she can aid in her own defense.

“My defense is simple: She was criminally insane,” Ray said Wednesday.

Gilbert is set to be arraigned on the indictment Friday morning in Ulster County Court, Ray said. He said he plans to enter a not guilty plea on behalf of his client.

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Headed to her arraignment on the initial murder charge late last month, a handcuffed Sarra Gilbert, wearing an orange jailhouse jumpsuit, said: “I love my family and I’m very sorry.”

Mari Gilbert served as a vocal advocate in the pursuit of justice for her daughter Shannan, a sex worker who went missing in May 2010. The search for Shannan Gilbert later uncovered 10 sets of remains that police said may have been the work of one or possibly more serial killers. Shannan Gilbert’s body was later found in Oak Beach in December 2011. Investigators eventually ruled that her death was unrelated to the serial murders.

Sarra Gilbert killed her mother while out on bail in an animal cruelty case in which she is accused of drowning her pit bull puppy, Ulster County Assistant District Attorney Emmanuel Nneji said.

Gilbert, the mother of a 7-year-old boy, has schizophrenia, Ray said.

According to court documents, at about 10 a.m. July 23, inside her Warren Street home, Sarra Gilbert “intentionally repeatedly stabbed” her mother with the kitchen knife and struck her with a fire extinguisher, causing her death. Family members asked police to check on Mari Gilbert’s condition after they grew concerned when she didn’t answer her phone, authorities said.

Last month Ray said Sarra Gilbert, who had been hospitalized in the past year for mental health issues, was not taking her medication and was “hearing voices” in the days before the killing, and had been fighting with family members for custody of her son, who is now living with his father’s family.