The HSCA commissioned a number of expert scientific studies to re-investigate the physical evidence of the JFK assassination. In comparison to witness testimony and government documents, the committee felt that such investigations would particularly benefit from the scientific advances of the fifteen years since the
Warren Commission. A technique using
neutron activation analysis (NAA), a form of what has become known as
comparative bullet-lead analysis (CBLA), was used to analyse the bullet lead from the JFK assassination. It revealed that it was highly likely that only two lead bullets were the source of all the following pieces of evidence: the mostly-intact stretcher bullet, fragments found in the
presidential limousine's front seat and rug, fragments recovered from JFK's brain autopsy and fragments recovered from Governor
Connally's wrist. Additionally, the location of the shooter (at the 6th floor
Texas School Book Depository window) was determined using trajectory analysis. The origin of the rifle bullets was calculated using the location of the presidential limousine and its occupants combined with the bullet wounds found on the president and governor. With the benefit of authenticated photographs, x-rays and notes from the
Kennedy autopsy, a nine-doctor panel of expert pathologists reviewed and corroborated the Warren Commission's medical findings. Although the HSCA medical panel was critical of the thoroughness and methodology of the original autopsy, they concurred, although Cyril Wecht dissented, with the Warren Commission's conclusion that two, and only two bullet wounds entered from above and behind (the direction of Oswald in the Book Depository). Their conclusion that the President was struck by a bullet that entered in the right rear of the head near the cowlick area and exited from the right front side of the head differed from a diagram in the Warren Commission's report showing this entrance wound low in the back of the head.
Fingerprint and handwriting analysis The authenticity of several
fingerprints and a palm print found on assassination-related materials was reaffirmed by a fingerprint expert. Lee Harvey Oswald's prints were found on the trigger guard and underside of the
Mannlicher–Carcano rifle used to shoot the president, the brown paper container used to transport the rifle, several cardboard boxes in the sniper's nest and on the magazine order form to purchase the rifle.
Dictabelt audio recording Although the HSCA had prepared a draft report confirming the
Warren Commission's single shooter theory and finding no evidence of conspiracy, at the eleventh hour, the committee was swayed by a since-disputed acoustic analysis of a dictabelt police channel recording. Although there has been some recent back-and-forth between different researchers, the HSCA's acoustic analysis is widely considered to be discredited. == Witness auditions ==