In October 2000, while walking along the shores of the "Great Salt Lake" near Salt Lake City, two hunters made a gruesome discovery. In a plastic bag, they found a white sock, a shirt, a few bones and a human skull to which long blond hair was attached. Despite their best efforts the police was unable to identify the victim. They nicknamed her "Saltair Sally" after a resort near where the remains were found. A search through missing person records, a comparison of dental records, widespread distribution of composite pictures and the description of personal effects, were of no help. Finally, the authorities abandoned their research and the case "Saltair Sally" was closed.
Seven years later the authorities got wind of a new identification technique, "stable isotope ratio mass spectrometry" (SIRMS), and decided to use it. To understand the principle of SIRMS, one must know that every molecule of our body not only made up of different elements, but different ratios of the stable isotopes of these elements. In the case of oxygen for example, the most abundant isotope (99.8%) is oxygen-16 whose nucleus contains 8 protons and 8 neutrons. The balance (ca. 0.2%) is represented by oxygen-18 which has two extra neutrons in the nucleus (there are also trace amounts of oxygen-17). The SIRMS technology is able to determine the relative amounts of these isotopes, but more importantly how they relate to geographical considerations.
Imagine what happens when rain-laden clouds travel from the Pacific Ocean to the interior. Let’s say, for example, to Salt Lake City where the victim was found. Drops of water with the greatest concentration of the heavier O-18 will fall first, leaving behind, in the clouds, isotopically lighter water, i.e. with a lower O-18/O-16 ratio. Given that drinking water has its origins in rainwater, people living near the ocean absorb more O-18 than those who live inland. As the oxygen isotopes are incorporated into all parts of the body it explains how hair analysis can be used as a forensic tool.
If Saltair Sally had lived in Salt Lake City, in the weeks before her death the section of hair close to the scalp hair should reflect the local isotopic signature. By contrast, if she came from the Pacific coast one would have expected a greater concentration of O-18. To the investigator’s surprise the analysis of Saltair Sally’ hair showed different sections of varying O18/016 ratio. Some were consistent with the Utah environment but others were characteristic of the Pacific Northwest. This led the investigators to believe that over the last years of her life, the victim had traveled several times between Salt Lake City and the coast, and therefore must have originated from there. As a result, the police moved their search from Utah to the Pacific Northwest.
On August 7, 2012, twelve years after the discovery of the body, the police announced that they had identified Saltair Sally. Her name was Nikole Bakoles. Originally from Washington State, she had moved to Utah in 1998 and, as suggested by the SIRMS hair analysis that was performed, returned home to visit her family. She had been reported as a missing person to the authorities of Washington State but the information had not been passed on to the Utah police. Now that the victim has been identified and confirmed by DNA testing, police now have to find the person who committed the crime. Hopefully it will not take another twelve years.