In contrast, from 1955 to 1963, atmospheric radiocarbon levels almost doubled.Since then they have been dropping back toward natural levels.However, the researchers suggested that soft tissue radiocarbon content would be transferred to, and preserved in, the pupal cases of insects whose larvae feed on these tissues.Such insects are simply another link in the food chain.Now, new applications for the technique are emerging in forensics, thanks to research funded by NIJ and other organizations.In recent years, forensic scientists have started to apply carbon-14 dating to cases in which law enforcement agencies hope to find out the age of a skeleton or other unidentified human remains.Over the past six decades, the amount of radiocarbon in people or their remains depends heavily on when they were born or, more precisely, when their tissues were formed.
Therefore, the radiocarbon level in those tissues post-mortem would indicate the year of death.
Radiocarbon levels in teeth formed before then contained less radiocarbon than expected, so when applied to teeth formed during that period, the method was less precise.
To determine year of death, the researchers used radiocarbon levels in soft tissues.
The researchers found that year-of-death determinations based on nails were accurate to within three years.
The generally poor post-mortem preservation of soft tissues would be a limiting factor to this approach.