Cortlandt Cunningham, of the Firearms Identification Unit of the FBI Laboratory, testified that he compared the four empty cartridge cases found near the scene of the shooting with a test cartridge fired from the weapon in Oswald’s possession when he was arrested. Cunningham declared that this weapon fired the four cartridges to the exclusion of all other weapons. Identification was effected through breech face marks and firing pin marks.[C4-571] Robert A. Frazier and Charles Killion, other FBI firearms experts, independently examined the four cartridge cases and arrived at the same conclusion as Cunningham.[C4-572] At the request of the Commission, Joseph D. Nicol, superintendent of the Illinois Bureau of Criminal Identification Investigation, also examined the four cartridge cases found near the site of the homicide and compared them with the test cartridge cases fired from the Smith & Wesson revolver taken from Oswald. He concluded that all of these cartridges were fired from the same weapon.[C4-573] Cunningham compared four lead bullets recovered from the body of Patrolman Tippit with test bullets fired from Oswald’s revolver.[C4-574] He explained that the bullets were slightly smaller than the barrel of the pistol which had fired them. This caused the bullets to have an erratic passage through the barrel and impressed upon the lead of the bullets inconsistent individual characteristics which made identification impossible. Consecutive bullets fired from the revolver by the FBI experts could not be identified as having been fired from that revolver.[C4-575] (See app. X, p. 559.) Cunningham testified that all of the bullets were mutilated, one being useless for comparison purposes. All four bullets were fired from a weapon with five lands and grooves and a right twist[C4-576] which were the rifling characteristics of the revolver taken from Oswald. He concluded, however, that he could not say whether the four bullets were fired from the revolver in Oswald’s possession.[C4-577] “The only thing I can testify is they could have on the basis of the rifling characteristics--they could have been.”[C4-578] Nicol differed with the FBI experts on one bullet taken from Tippit’s body. He declared that this bullet[C4-579] was fired from the same weapon that fired the test bullets to the exclusion of all other weapons. But he agreed that because the other three bullets were mutilated, he could not determine if they had been fired from the same weapon as the test bullets.[C4-580]