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History of Forensics: Murder & the Metal Detector
Searching a stream with a modern metal detector
Necessity is the mother of invention. In 1881 assassin Charles Guiteau fired two shots at the 20th President of the United States James A., Garfield. One of the bullets lodged in his body and did not exit. President Garfield was rushed to the hospital where he lived for 80 days before his death. Doctors were hesitant to do surgery because they couldn’t determine where the bullet was lodged. Famed inventor Alexander Graham Bell learned of the President’s injury and the inability to locate the bullet. He set about to develop a device to “see” the bullet through the skin. Bell developed a coiled detector and performed several successful experiments on finding bullets in animals (sheep) before rushing to the hospital. His first attempts to use the detector were unsuccessful so Bell went back to his laboratory and made several adjustments. Returning to the hospital he tried again without success.
Following the President’s death from his condition Bell went to the autopsy with his metal detector and it worked very well. Some historians believe that a new invention owned by President Garfield interfered with the operation of the new metal detector. What was the new invention you ask…the coil spring mattress. The metal coils essentially “overloaded” or “masked” the signature of the bullet making it invisible. Modern investigators often run into the same problem when searching ground littered with metal trash. The difference is that modern CSIs are very aware of this cancellation. Modern metal detectors can actually be “tuned” to ignore certain signatures and limit their sensitivity to that of the evidence being searched for. I’ll need to do a future posting on modern metal detectors and their capabilities. Being a new invention however, Bell was totally unaware of the coil springs in the mattress and apparently didn’t account for them. Think of it. Two brand new inventions cancelling each other out. It was an unfortunate incident but both inventions continue to enrich our lives.
