Investigating a cold case using high-resolution multi-isotope profiles in human hair

Abstract Human remains, later named “Madame Victoria”, were discovered in 2001 near the Royal Victoria hospital in Montreal but were never identified by forensic practitioners. We use multi-isotope hair profiles to investigate Madame Victoria’s travel and diet history. Based on carbon isotope abundances, Madame Victoria had a stable diet and values typical of eastern Canada. Nitrogen isotope ratios are more positive than average Canadians, and increase sharply over the last two months of her life, likely reflecting a rapid health deterioration. Hydrogen isotope abundances are typical of eastern Canada, and become stepwise more positive throughout the hair profile. Based on hydrogen isotope data, Madame Victoria moved progressively from either a western Ontario or northern Quebec locality towards Montreal over the last 3 years of her life stopping multiple times along the way. The strontium isotope ratios are constant throughout the hair profile and equal to the isotopic value of the soil exchangeable strontium at the site where the body was discovered. This observation, combined with hair major and trace elemental data, indicates that strontium from soil diffused and replaced the original hair strontium post-mortem. This study shows the interest of multi-isotope hair profiles to focus investigations on cold cases but also underlines the need for further work to take advantage of metal and metal isotope data.