Last winter, police in Denver, Colorado, announced that they had solved the cold-case murders of four women who had died about 40 years ago, all of whom had been the victims of one man—a previously unknown serial killer named Joe Michael Ervin. It took years of old-school police work and a cutting-edge investigative technique called forensic genetic genealogy (FGG). It took the combined efforts of law enforcement in Colorado and Texas, along with support from the Bureau of Justice Assistance (BJA), which used two different grants to help crack the case.