The Delaware County man accused of killing his caseworker and wounding a psychiatrist at an office in Mercy Fitzgerald Hospital in July pleaded not guilty on Wednesday.

Richard Plotts, 49, of Clifton Heights, shackled and wearing a red prison jumpsuit, stood silently during the formal arraignment before Delaware County Court Judge Mary Alice Brennan.

Attorney Charles Williams, a public defender, entered he plea on behalf of Plotts, who was charged with first- and third-degree murder in the slaying of caseworker Theresa Hunt, and aggravated assault for shooting his psychiatrist, Lee Silverman.

On July 24, Plotts went to the Yeadon hospital complex for an appointment. He allegedly shot Hunt, 53, in the head and then exchanged gunfire with Silverman who pulled out his own gun and shot Plotts.

Silverman, who authorities said acted in self defense, received a graze wound to the head and was hit in his hand. Plotts also was wounded in the exchange and was in critical condition for several days following the shooting.

Plotts is being held without bail at the George W. Hill Correctional Facility in Delaware County.