In a crevice between the butt plate of the rifle and the wooden stock was a tuft of several cotton fibers of dark blue, gray-black, and orange-yellow shades.[C4-64] On November 23, 1963, these fibers were examined by Paul M. Stombaugh, a special agent assigned to the Hair and Fiber Unit of the FBI Laboratory.[C4-65] He compared them with the fibers found in the shirt which Oswald was wearing when arrested in the Texas Theatre.[C4-66] This shirt was also composed of dark blue, gray-black and orange-yellow cotton fibers. Stombaugh testified that the colors, shades, and twist of the fibers found in the tuft on the rifle matched those in Oswald’s shirt.[C4-67] (See app. X, p. 592.) Stombaugh explained in his testimony that in fiber analysis, as distinct from fingerprint or firearms identification, it is not possible to state with scientific certainty that a particular small group of fibers come from a certain piece of clothing to the exclusion of all others because there are not enough microscopic characteristics present in fibers.[C4-68] Judgments as to probability will depend on the number and types of matches.[C4-69] He concluded, “There is no doubt in my mind that these fibers could have come from this shirt. There is no way, however, to eliminate the possibility of the fibers having come from another identical shirt.”[C4-70] Having considered the probabilities as explained in Stombaugh’s testimony, the Commission has concluded that the fibers in the tuft on the rifle most probably came from the shirt worn by Oswald when he was arrested, and that this was the same shirt which Oswald wore on the morning of the assassination. Marina Oswald testified that she thought her husband wore this shirt to work on that day.[C4-71] The testimony of those who saw him after the assassination was inconclusive about the color of Oswald’s shirt,[C4-72] but Mary Bledsoe, a former landlady of Oswald, saw him on a bus approximately 10 minutes after the assassination and identified the shirt as being the one worn by Oswald primarily because of a distinctive hole in the shirt’s right elbow.[C4-73] Moreover, the bus transfer which he obtained as he left the bus was still in the pocket when he was arrested.[C4-74] Although Oswald returned to his roominghouse after the assassination and when questioned by the police, claimed to have changed his shirt,[C4-75] the evidence indicates that he continued wearing the same shirt which he was wearing all morning and which he was still wearing when arrested.