The Justice Department has issued its first procedures for how the FBI and other department law enforcement agencies should ask eyewitnesses to identify suspects using photo lineups and how federal prosecutors weigh that evidence to avoid erroneous convictions.

The new departmentwide policy is intended to lower the risks of investigators influencing a witness, even unintentionally, when presenting photo arrays of possible suspects.

“Eyewitness identifications play an important role in our criminal justice system, and it’s important that we get them right,” U.S. Deputy Attorney General Sally Q. Yates said in a statement Friday that followed years of increasing attention from scientists and policing groups to the reliability of such testimony.

In the two-page memo, Yates called on heads of the FBI, Drug Enforcement Administration, Bureau of Alcohol, Tobacco, Firearms and Explosives and U.S. Marshals Service to update several practices to align with the new policy.

Those include whenever possible using a “blind” photo lineup in which an investigator presenting the photos either does not know who suspect is, or, if that is not practical, does not know which photo the witness is viewing. The procedures also include recording the ID process by video or audio, and documenting the witness’s confidence in an identification at the time it is made, preferably through the witness’s own words.

“With today’s procedures, we’re taking one more step to ensure that law enforcement officers obtain the most reliable evidence possible during a criminal investigation and that all Americans can have confidence in the fairness of our criminal justice system,” Yates said.

Witness recollections are wrong about one-third of the time, researchers have found, due to human limits on vision and memory that can be exacerbated by emotional responses to crimes and widely varying law enforcement practices.

Statements that an arrest has been made, that a witness picked the “right” or “wrong” individual or even repeat showings of a photo and other nonverbal cues can have a psychological effect that leads to misidentifications.

“Unknown to the individual, memories are forgotten, reconstructed, updated, and distorted,” the National Academy of Sciences reported in 2014 as it made a series of recommendations to prevent wrongful arrests.

The NAS, the nation’s top scientific organization, endorsed changes similar to those urged by the International Association of Chiefs of Police in December 2013, calling on police departments to adopt new guidelines for photo lineups and videotaping witness interviews, among other measures.

“It’s good. It’s needed, and I don’t know if it’s still controversial, but what the Department of Justice announced today is in keeping with the findings of the NAS and what IACP has been urging all along,” said Bill Brooks, a member of the association’s board of directors and chief of the Norwood, Mass., police department.

While some practitioners caution that changes could hinder investigations or confuse witnesses, Brooks said the new guidance creates a more “pristine” and “sanitized” system that will help police and prosecutors convince jurors evidence is free of police influence, boosting confidence in the justice system.

Yates’s memo, and an accompanying 10-page checklist of procedures, update a 1999 DOJ department report, and direct federal prosecutors across the country to review the procedures before deciding to charge a suspect who was identified through a photo array done by federal, state, or local police.

The memo does not imply that identifications made without following the procedures are unreliable or inadmissible in court. Still, it directed the heads of the FBI, Drug Enforcement Administration, Bureau of Alcohol, Tobacco, Firearms and Explosives and U.S. Marshals Service to ensure that investigators avoid making statements or taking actions that might suggest who the suspect is, including not volunteering information about the case or stating a suspect is in custody.

Witnesses should view photos away from the presence of other people, and sign an acknowledgment that they have received written and oral instructions, including that the perpetrator might or might not be included in the photo array. The array should include the photo of only one suspect in a case and at least five non-suspects of similar description. The array should not include information that would reveal a person’s identity, previous arrests or the source of the photograph, the procedures state.

“The Department of Justice should be applauded for adopting eyewitness practices that flow from the best advances in scientific research,” said Peter Neufeld, co-founder of the Innocence Project, which has called for the changes as part of its advocacy for prisoners seeking exoneration through DNA testing. “It will greatly strengthen identifications that comply with these guidelines to convict the guilty, and at the same time reduce the danger of unfairly sweeping up the innocent.”