The Prince George’s County Police Department is transforming how detectives conduct photo lineups in an effort to prevent innocent people from going to prison.

Starting this spring, detectives must show witnesses photos of potential suspects one at a time on separate pieces of paper rather than all at once on a single page. Lineups must also be “blind,” which means a detective unfamiliar with the case must present photos to witnesses instead of an officer investigating the crime.

The method is called the “double-blind sequential lineup.” The goal is to reduce chances that witnesses would falsely identify suspects or that detectives would unwittingly nudge witnesses to choose a particular photo.

“You don’t want to catch the wrong guy because now you’re messing with someone who is innocent and the bad guy is still out there,” said Carlos F. Acosta, inspector general for the Prince George’s police.

The county is not alone in overhauling its lineup policies. Baltimore adopted new photo lineup policies in the fall, while the practice has become the norm in Dallas, North Carolina, Philadelphia and other jurisdictions. And late last month, Maryland state Sen. Catherine E. Pugh (D-Baltimore) introduced a bill in the General Assembly that would require all law enforcement agencies to change their procedures to blind but not sequential lineups.

But while Prince George’s — and possibly the entire state — joins other localities changing photo lineup practices, it will still be among the minority. That’s because despite decades of social-science research and robust endorsements from law enforcement leaders heralding the double-blind sequential lineup, there is still doubt among policy experts as to whether the procedure is an improvement.

“There was a time when everyone in the field who was involved in the research or police took the position that sequential is better than simultaneous and blind is better than non-blinded,” said Steven Clark, a psychology professor at the University of California at Riverside who studies eyewitness identification and photo lineups. “Now it’s controversial. Things have really changed.”

In the past few years, at least three academic papers have emerged bucking nearly 30 years of research favoring the practice. Before, researchers thought sequential lineups would reduce false identifications without affecting correct identifications. But more and more, some are saying that while chances of mistaken identifications decrease, so does the likelihood of accurate identifications.

For some, there is no debate. They say the double-blind sequential lineup makes sense in real-life investigations.

Prince George’s police Capt. George Nichols said that under current lineup methods, witnesses “Frankenstein” a suspect based on the six photos they see on a page. They compare the features of each, maybe selecting the nose on one and the eyebrows on another. Then, they get overwhelmed.

“With the sequential, you show them one picture at a time so they’re comparing what they see to their memory versus comparing to other suspects on the same page,” said Nichols, assistant commander of the Criminal Investigation Division. “It’s more of a cleaner ID.”

The consequences of a false identification and bad eyewitness memories can be devastating. About 75 percent of wrongful convictions later overturned through DNA evidence originally involved bad eyewitness identifications, according to the nonprofit Innocence Project. One of the most notable wrongful convictions came from Virginia. Thomas Haynesworth spent 27 years in prison there for rapes he did not commit. Victims misidentified him in person and in photo arrays.

Most of the controversy lies in whether the photos should be presented simultaneously on a single page, as is common practice, or sequentially.

“It is somewhat sobering to realize that it is currently unknown whether the recommended procedures, no matter how sensible they might seem, are diagnostically inferior, diagnostically equivalent, or diagnostically superior to the alternative lineup procedures they would replace,” according to a 2012 paper published by the American Psychological Association.

Policymakers, law enforcement groups and psychologists are hungry for definitive answers. Last week, the country’s top social scientists, legal experts and criminal-justice advocates convened in the District to discuss eyewitness identification and lineup changes at the National Academy of Sciences. After months of study, the committee will issue a report and recommendations on the debate.

University of Virginia professor Brandon Garrett is part of that committee and has pushed eyewitness identification changes in the commonwealth. In a survey last year, Garrett found that fewer than half of the departments in Virginia conducted blind lineups, while only a handful — 6 percent of 144 agencies — adopted the model policy recommending double-blind sequential lineups.

“A lineup is designed to test someone’s memory, but a bad lineup can change someone’s memory,” Garrett said. “These policies are important to make sure police don’t work with an eyewitness in a way that would change their memory. That is something that doesn’t do right by the victim.”

In the District, investigators have the option of selecting whether lineups are simultaneous or sequential, but the photo array must be blinded.

Blind presentations are meant to reduce the chance that an investigator would unconsciously bias a witness to a certain photo, said Shawn Armbrust, executive director of the Mid-Atlantic Innocence Project, which helped exonerate Haynesworth and is backing Pugh’s bill.

“It’s like a drug trial, and the person handing out the placebo doesn’t know it is a placebo,” Armbrust said.

Maryland requires agencies to have written policies dictating how lineups are conducted. But the bill Pugh introduced recently would mandate changes.

The changes are meant to give everyone a “fair break and make sure eyewitness identification is appropriate,” Pugh said. The judiciary committee is expected to hear Pugh’s bill in March, shortly before changes in Prince George’s are expected to become official.

Armbrust applauds the Prince George’s police initiative and hopes other Maryland agencies will follow suit. That way, everyone has “a chance of having the most accurate identification procedures,” she said.

“If I’m arrested in one of the majority counties that haven’t adopted these policies, I’m at a disadvantage,” Armbrust said. “You have an uneven quality of justice throughout the state.”