On November 2, at Judge Thayer’s request, District Attorney Williams borrowed from Van Amburgh a plug gauge, a device for measuring the diameter of a gun barrel. He found Sacco’s pistol barrel to measure .3045 inches. Hamilton’s measurement had given the diameter as .2924 inches, but Williams thought little of the discrepancy since he himself had never seen a plug gauge before and felt he might easily have made a mistake. However, when Hamilton, on December 4, in the presence of the clerk of court, checked Sacco’s pistol with the gauge, he confirmed Williams’ measurement. Hamilton now observed that the fouled rusty barrel was shiny and, according to his later testimony in a special hearing before Judge Thayer, his first thought was that the court had been cleaning it. “I could not conceive in my mind why you would do it,” he told Thayer, “but I said to myself no one else could have done it.... I immediately dispelled it because I said, no court would alter an exhibit.”
Whatever Hamilton’s opinion of the altered condition of the barrel and the variations in his first and second measurements, he afterward maintained that when he examined Sacco’s automatic on December 4 it never occurred to him that the barrel was anything but the original.
Acting on Thompson’s request to make fresh firing tests, Judge Thayer on February 11 called in Van Amburgh to inspect Sacco’s Colt and determine its condition. With the district attorney present, Van Amburgh took the gun from the clerk of court and prepared to disassemble it. No sooner had he drawn back the slide than he saw that the barrel was not the barrel he had last examined. It looked brand-new. There was even a film of cosmoline on it.
“Someone has switched barrels,” he at once told Williams.
The two hurried to Judge Thayer. Thayer, after listening to them, announced that he would hold an investigation.
Two days later he began hearings in his chambers with only Moore, Williams, Hamilton, Van Amburgh, and a stenographer present. Press and public were barred, unaware even that such hearings were taking place. They lasted just over three weeks. At the opening Clerk Worthington brought in the three pistols. The briefest examination made it clear to everyone that Sacco’s Colt had acquired a new barrel. Hamilton, not at all abashed that every finger seemed to point to him, admitted that the new barrel must have come from one of his pistols, but insisted that he had not made the switch. In his opinion this had been done by someone connected with the prosecution. After examining the fouled barrel in one of his own new guns under a microscope, Hamilton stated that he was unqualifiedly of the opinion it was not the Sacco barrel.
Williams accused Hamilton of working the substitution with the idea of later making the discovery himself so that he could then demand a new trial. Repetitious and acrimonious, the arguments went on each day until five o’clock, but no one in the closed chambers had any real doubt as to who had switched the barrels. Even Moore, arguing bravely that this was more dirty work on the part of the district attorney’s staff, knew that Hamilton’s deft fingers had done it.
At the conclusion of the hearings Thayer reserved judgment as to who had made the substitution and whether or not it had been accidental. He ruled merely that the barrel in the new pistol had come from Sacco’s Colt and he ordered the fouled barrel replaced and the three pistols delivered into the clerk’s custody “without prejudice to either side.” The prejudice, however, was not so easily obliterated. Hamilton’s chicanery had undermined his value as a witness, past or future. Although he was to continue his association with the defense almost to the end, he would prove only a detriment—expensive, untrustworthy, and untrusted.
Almost at the very time Hamilton was discrediting himself in Dedham, Van Amburgh, in Bridgeport, Connecticut, was demolishing his own ethical and technical reputation in the Harold Israel case. Israel was a young ex-soldier of small intelligence who had been charged with the murder of Father Hubert Dahme, pastor of St. Joseph’s Catholic Church. On the evening of February 4, 1924, Father Dahme was strolling along Bridgeport’s Main Street when a man approached him from the rear, placed the muzzle of a revolver close to his head, and fired. Several witnesses saw the murderer run from the scene.