Forensic Trivia: “Smithereens”
January 19, 2014
images (7)On Dec. 21, 1988, Pan American flight 103, originating in Frankfort, Germany landed at London’s Heathrow Airport, and after loading passengers and luggage, took off for New York’s JFK airport at 18:25 p.m. At approximately 19:02 p.m. air traffic control lost contact with it. A few seconds later the radar showed the plane’s blip on the screen fracture into five separate ones, trailing away from each other. The plane had exploded and the debris rained down on the Scottish town of Lockerbee.
243 passengers and 16 crew, dead, as well as 11 residents from Lockerbee.
This was one of the most famous plane crashes in history, both for the horror it was, the subsequent political implications, and the forensic investigation that ensued leading to the arrest and conviction of one of the terrorists involved.
The USA’s FBI, and the British equivalent of our NTSB, the Air Accidents Investigation Branch, laboriously collected every piece of wreckage from the plane, and pieced together the smithereens they found into a whole plane.
How did forensic scientists look at this reconstruction, and what did it tell them? The heartbreak of loss was unimaginable, the forensics task daunting. The only possible closure was to solve the riddle of what happened.
The importance of collecting as much of the Boeing 747’s wreckage as possible was that the reconstructed plane, coupled with the results of the analysis of each piece for explosives residue, would enable the explosives experts to determine where the bomb was located on the plane.
The investigative teams combed the debris field created when the parts of the plane fell onto Lockerbee. Even the tiniest pieces were collected and engineers familiar with the plane’s design reconstructed it in a large hangar.
The Debris Field
The Debris Field
Each piece was also tested for chemical residues known to be left when substances like Pentex or Semtex explode. Each piece was also examined microscopically for the telltale particles of explosives residue left behind.
This residue is analyzed by forensic chemists using the standard protocol for identifying unknown compounds. The protocol involves first, separation of the residue into its component parts, using various forms of chromatography. The most definitive form being gas chromatography. The results are injected into a mass spectrometer which can, with the accuracy afforded to the matching of fingerprints, identify the component compounds in the residue.
The results for Pan Am 103 found that the explosion occurred in the cargo hold just under the P in the Pan Am logo on the fuselage. This told the investigators that the bomb was loaded onto the plane in Frankfurt, at the flight’s origin. A further investigation of the luggage which was also collected and analyzed, revealed the exact piece of luggage, a brown Samsonite case, that had carried the bomb. Inside that Samsonite case was a Ghettoblaster cassette player, stuffed with Semtex. Scientists can piece this together because the pieces of wreckage closest to the blast have the most residue.
This fact enabled them to trace the clothing from that suitcase to a shop in Malta where sales receipts started the trail that eventually led to Abdelbaset al-Megrahi and Lamin Khalifah Fhimah. Megrahi was found guilty and went to jail. A Scottish judge released him when it was determined that he had terminal cancer. Fhimah was exonerated. The investigation also led to a connection to Muammar Gaddafi, leader of Libya. After a good deal of international pressure, he eventually paid compensation to the families of the victims.
It should be noted that all plane crashes where explosives or bombs are suspected to be the cause, are analyzed the same way.
TWA Flight 800, off Long Island, in 1996, was reconstructed at the old Gruman Aviation Plant in Calverton, L.I. The results of this investigation were not as definitive because the wreckage needed to be recovered from the ocean bed, water possibly removing the explosive residue.
The bottom line? Tiny pieces of evidence can lead to the solution of the biggest crimes.