A Pana man has plead not guilty to new charges of first degree murder of his infant son. Robert Stivers was arrested in February after his four month old son was taken to a St. Louis hospital for treatment of injuries suffered allegedly at the hands of Stivers. The new charges state that Stivers shook and squeezed the child causing injury. The charge replaces a previous charge that has since been dismissed, that merely states that Stivers shook his son. If found guilty, Stivers could face up to 60 years in prison.