Thank you for submitting your item for appraisal. Judging from the information you provided it should be a sketch by Jerry McJunkins who was the courtroom artist at the time. The quality of his drawings are quite above average and I assume the drawing in your possession is of similar quality. Jerry McJunkins drawings are not being sold at auction. The estimate is based on similar drawings by lesser known artists sold at auction. "Asking prices" in the trade can be higher and vary.