NEW CITY - The woman alleged to be the brains behind a "murder-for-money" plot in Rockland pleaded not guilty at her arraignment in Rockland County Court Wednesday.

According to investigators, Diana Nadell, 50, recruited the help of three women to murder her 80-year-old mother-in-law Peggy.

It was the second arraignment for Nadell, who had her charges upgraded from second- to first-degree murder. The courtroom was filled with emotion as many in attendance wore "Justice for Peggy" pins.

Nadell and Andrea Benson allegedly traveled from Washington, D.C. in January to the well-known political activist's Valley Cottage home. Authorities say the two brutally beat and stabbed Peggy Nadell to death, leaving a knife stuck in her chest.

Prosecutors say Nadell hatched the plot so she could get her hands on part of a $4 million inheritance.

The other three women involved in the deadly plot have all pleaded guilty for their part in the crime and have agreed to testify against Nadell in exchange for lesser sentences. Benson admitted to shoving Peggy, but says Diana Nadell was the one who stabbed and beat her.

Nadell is being held at the Rikers Island jail while Benson is being held in Rockland County so the two are separated.

Rockland County District Attorney Tom Zugibe says he's looking to put Nadell behind bars for the rest of her life. "She is charged with murder in the first degree, based upon the fact that this is a murder-for-hire,” he says. “We will be seeking life without parole upon conviction."

Nadell is expected back in court on July 30. Her bail is now set at $5 million.