In 1988, Barry Gibbs was convicted of murdering a prostitute. Just two weeks ago, that conviction was thrown out when the eyewitness who fingered Gibbs said the police lineup was rigged. Where do officers find people for a lineup?
In jail. The investigating detective typically plucks lineup fodder—known as "fillers," "dummies," or "known innocents"—from the in-house lockup. Most states require at least four fillers to be in a lineup. To have a positive identification stand up in court, the suspect can't be the only person in the lineup who matches any distinctive characteristics that the witness remembers. If an eyewitness recalls that the culprit had John Kerry-style hair, then a detective has to find fillers with Kerry coifs, not just four older white guys.
Sometimes cops can't find all the fillers they need in jail—there's a limited supply of inmates, and some are either too dangerous to deal with or just don't want to cooperate. In such instances, a detective might look for stand-ins in the county or central city jail; he also might pull in other cops, office workers, or sometimes even people on the street. For example, if Manhattan cops find someone on the street with the right look, they will pay him or her $10 to participate in a lineup.
There are two types of police lineups: investigatory and confirmatory. For an investigatory lineup, in which the detective susses out whether he's got the right man, the stand-ins usually get rounded up in about an hour—it's difficult to hold a suspect who hasn't been arrested for much longer. Police might take more care and more time to assemble a confirmatory lineup, in which a witness is called in to verify the identity of someone who's already been arrested.
Even the most thorough detective often has to settle for fillers who share only the suspect's broadest characteristics, like race and height. Perhaps that's why it's common to find that convictions overturned based on new evidence (such as DNA) rested on live lineup identifications.
Some criminal-justice experts and the U.S. Department of Justice now recommend using digital photo spreads. For one, it's easier to find fillers with specific features by using thousands of booking photographs. Most American police departments choose six photos and arrange them in two rows of three—what's called the "six pack." Canadian police typically use 12 photos in each virtual lineup.
But some jurisdictions, like New York City, still require that a live lineup be used for an eyewitness identification to be admissible in court. A few police departments have tried to improve their lineup methodology by hiring outside consultants to pull fillers rather than detectives, who are often overworked and poorly trained in lineup design.