Before responding to a job offer from a forensic laboratory in Toronto, Greenfield worked as a forensic scientist in Great Britain, where he became familiar with the relatively new wave of DNA research. In 1999, he participated as a forensic scientist in the case of a child's murder. The murder was discovered when a woman walking her dog noticed a partially buried bag that contained the severed limbs of a young child. The child's limbs were tested for DNA, which determined that the victim was a female of early school age. Greenfield then proceeded to compare the child's DNA to a number of DNA databases grouped by race/ethnicity although this was not considered to be a reliable practice at the time. Greenfield found what he determined to be a probability match of the child's DNA with the East Indian database. Although recognizing this conclusion was problematic at the time, this information on the child's ethnicity was released to the public. In response, a school teacher contacted the police about an East Indian child who was missing from her class at the approximate time of the discovery of the child's remains. Fingerprints from the missing child's schoolwork matched those of the murdered child. The father and stepmother of the child eventually confessed, reporting that the father had become angry at his daughter, and in a rage, beat her to death. The parents were convicted.