Then the list disappeared.

After a year of criticism from privacy advocates and genealogy experts, the owner of a popular DNA-sharing website had decided law enforcement had no right to consumer data unless those consumers agreed.

"It was devastating to know that there's information out there," Fields said. "It wasn't fair."

So he persuaded a judge to grant him access to the entire database, the genetic records of more than 1 million people who never agreed to a police search. It was the first court order in the nation for a blanket consumer DNA search, kept secret from those whose genetic code was involuntarily canvassed.

Genealogical databases are a potential gold mine for police detectives trying to solve difficult cases.