According to my friend, Gunnery Sergeant Carlos Hathcock, the former senior instructor for the U.S.Marine Corps Sniper Instructor School at Quantico, Virginia, it could not be done as described by the FBI investigators. Gunny Hathcock, now retired [deceased 2003], is the most famous American military sniper in history. In Vietnam he was credited with 93 confirmed kills--and a total of over 300 actual kills counting those unconfirmed. He now conducts police SWAT team sniper schools across the country. When I called him to ask if he had seen the Zapruder film, he chuckled and cut me off. "Let me tell you what we did at Quantico," he began. "We reconstructed the whole thing: the angle, the range, the moving target, the time limit, the obstacles, everything. I don't know how many times we tried it, but we couldn't duplicate what the Warren Commission said Oswald did. Now if I can't do it, how in the world could a guy who was a non-qual on the rifle range and later only qualified 'marksman' do it?"
Craig Roberts' website is RifleWarrior.com
Harold Weisberg, Case Open, Carroll & Graf, 1994, refutes Gerald Posner, Case Closed.
Weisberg published Whitewash in 1965 and a series of books subsequent to that until his death this year.
Through his dozen FOIA lawsuits he obtained hundreds of thousands of pages of documents from the FBI, Justice Department and other agencies, filling sixty filing cabinets.
Weisberg states that Zapruder said he thought the shots came from his right, the direction of the "infamous grassy knoll" using the phrase from Case Open.
Assassination Science, James A. Fetzer Ph.D. ed., Catfoot/Carus, 1998 contains an article by David W. Mantik M.D., Ph.D., "Optical Density Measurements of the JFK Autopsy X-Rays". Dr. Mantik finds compelling evidence the anterior-posterior (front-to-back) skull x-ray is a composite (combination of two images) with a 6.5 mm diameter disc applied--not representing metal or bone, but a forgery.
In an examination of the back wound, Dr. Mantik notes the HSCA placed it precisely 1.1 cm inferior to the first thoracic vertabra, T1. After noting Humes' ignorance of the cross-sectional anatomy of the transverse processes, Mantik finds "the proposed trajectory therefore seems purely imaginary", hence the back wound resulted from a nonpenetrating wound.