Skepticism about the stronger claims used by witnesses in the 1970s and 1980s existed at the time. Researchers said in 1974 that the whole process was inherently subjective, and the FBI wrote in 1984 that hair analysis cannot positively match one single person. In the 1990s, DNA profiling was introduced as a key new technique into forensics investigations; it introduced a new level of certainty about matching suspects to evidence. DNA analysis of old cases from the 1970s and 80s, however, contradicted conclusions about a number of earlier matches on the basis of hair analysis.