During the afternoon of April 15, 1920, security guards Alessandro Berardelli and Frederick Parmenter were transferring payroll funds for a shoe factory in South Braintree, Massachusetts. Two men opened fire on the guards, killing them both and fleeing with more than $15,000, a tidy sum in those days. Witnesses told police the two gunmen were "Italian looking" and that one of them sported a dark handlebar mustache.
The only bits of evidence found at the scene were several shell casings that were manufactured by three different firms: Remington, Winchester, and Peters.
Two days later, the getaway car was found and traced to an earlier robbery that police believed had been arranged by Mike Boda, a local criminal. When police went looking for Boda at his hideout, they found not him but two men, Nicola Sacco and Bartolomeo Vanzetti. Vanzetti had a dark handlebar mustache, and Sacco possessed a .32 caliber handgun, the same caliber as the murder weapon. Sacco also had 29 bullets for the gun, all manufactured by Remington, Winchester, or Peters. The two men were arrested and charged with the double murder.
Police also discovered that Sacco and Vanzetti belonged to an anarchist movement that advocated violent political change. By the time the trial opened on May 31, 1921, before Judge Webster Thayer in Dedham, Massachusetts, the case had become America's first Red Scare. The defense team put together an alliance of anarchist, communist, and union leaders called the Sacco-Vanzetti Defense Committee, which labeled the trial a witch-hunt.
The case hinged on proving that the bullets that struck down the two guards came from Sacco's gun, but those bullets were so outdated that forensic examiners were unable to locate any unspent ammunition to test-fire for making a comparison. Ultimately, they resorted to using the ones they'd found on Sacco at the time of his arrest. A match was made, and Sacco and Vanzetti were convicted and sentenced to death. But the story didn't end there.
Albert Hamilton, an expert of questionable honesty, came forward saying that he had no doubt the bullets used to kill the two guards did not come from Sacco's gun. The defense petitioned for a retrial and, during the hearings, Hamilton showed his true colors.
In an odd performance, he brought two new .32 caliber Colt handguns to court and disassembled them, along with Sacco's gun. He then attempted to secretly exchange one of the new gun barrels for the one on Sacco's gun. Judge Thayer caught him, ordered that Sacco's gun be reassembled, and denied the petition for a new trial. Still, the story didn't end.
Because of continued protests by anarchists, in June 1927, a committee was formed to look into the case. America's leading firearms expert, Dr. Calvin Goddard of the Bureau of Forensic Ballistics in New York, entered the fray. At his disposal were two new forensic tools: the comparison microscope and the helixometer. The former enabled scientists to microscopically inspect and compare two different bullets, and the latter was a probe fitted with a light and magnifying glass that enabled them to examine details of the inside of a gun barrel. Again, the match was conclusive.
On August 23, 1927, the two killers died in the electric chair. Yet the controversy persisted. In 1961, and again in 1983, the case was reexamined, and on each occasion, Goddard's findings were confirmed.