The victim, Susan Trott, was killed in her own apartment in October of 2018 and was found after four days with a gash in her neck.
On Monday, a jury found Anya Johnston guilty of one count of murder in the second degree despite claims she was not of sound mind.
There was no apparent motive for the murder.
"Today, a jury found Anya Johnston guilty of the gruesome, fatal stabbing of her elderly neighbor Susan Trott, a vibrant and talented woman who was beloved by her family and friends," said Manhattan District Attorney Alvin Bragg in a statement. "Ms. Johnston's heinous and calculated actions reflected a blatant disregard for Ms. Trott's life, as she left her body to decompose for nearly four days after the stabbing. I hope the accountability delivered by today's guilty verdict can provide comfort to Ms. Trott's loved ones, who continue to heal from the deep trauma her death has caused. I thank our prosecutors for their diligent and thorough work that led to this conviction."
Johnston is expected to be sentenced on May 1.
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