A facial recognition database called FACES is helping police in Jacksonville, Florida identify suspects.
The system has already succeeded in identifying a repeat-offender on drugs offences named Willie Allen Lynch.
The forces is responsible for storing a collection of more than 33 million photos accessible by most law enforcement agencies in Florida.
"You have to have other information you use in conjunction with that match to lead you to get probable cause to arrest somebody," First Coast News Crime Analyst Mark Baughman told First Coast News.
However, privacy advocates has complained that the database is not mentioned in any police report and prosecutors told the judge Lynch's arrest was made through probable cause.
"My biggest issue is the lack of documentation and the lack of transparency," said attorney James Boyle of Boyle and Gowner.
Until this case, attorney Boyle sayd he'd never heard of the facial recognition database being used in Jacksonville for a criminal investigation.
"I'm unaware of any JSO policy that governs any kind of facial recognition program," Boyle said.