An attorney says the death of a New York woman won't end the quest to confirm her suspicions her daughter was a homicide victim.

Mari Gilbert's daughter Shannan Gilbert was a prostitute whose 2010 disappearance led to the discovery of 10 sets of human remains along a Long Island beach highway. Shannan Gilbert's body was found several miles away.

Police and prosecutors have said they don't think Shannan Gilbert was the 11th victim of a serial killer and they think she accidentally drowned. Mari Gilbert insisted they were wrong.

Mari Gilbert was stabbed to death in upstate Ellenville on Saturday. Police allege she was killed by another daughter, Sarra Gilbert.

Sarra Gilbert's lawyer hasn't commented.

But family attorney John Ray says Sarra Gilbert suffered from mental illness. He says he'll continue to seek answers in Shannan Gilbert's death.