She Took a Picture of the Man Who Attacked Her. It Didn’t Matter.

Last year, on a cool September afternoon around 2 o’clock, a friend who lives in my building was walking to the post office in Downtown Brooklyn when she was attacked by a stranger. She had been on the phone when she vaguely noticed someone in her periphery. Suddenly he was right in front of her, mimicking her movements as she tried to step away. Assuming the position of a linebacker, he tackled her to the ground, leaving her at the curb with various injuries.

He walked away, but before long he turned around and came back. By this point my friend, Laura, a slight artist in her 50s (who asked that I not use her full name because she continues to feel vulnerable) was safely inside the closest building. From behind a glass door, she was able to take a picture of the man with her cellphone. And there was other visual evidence: A nearby security camera had recorded the attack, footage of which my friend eventually watched in the company of detectives at the 84th Precinct.

The incident struck me not only because it happened in the middle of the day, to someone I know and care about, in what is considered a very safe part of Brooklyn, but also because of what followed procedurally and what it revealed about the still dubious place of technology in modern law enforcement.

On Oct. 23, five weeks after the attack that left Laura with bruises to her lower back, a chipped tooth and scrapes on her elbow and forearm, she was called in to the precinct house to identify a suspect. There were no actual people in the lineup; instead, she faced a presentation of eight pictures of different men who, she said, looked unnervingly similar.

“The idea that I might wrongfully accuse someone weighed on me,’’ she told me later. Although she could quickly eliminate five of the eight, she found it hard to distinguish among the remaining three — each of whom had a point at the top of his cranium, she noticed, and eyes that were cast downward.

She made a selection. Then, detectives told her that her assailant was No. 5; she had chosen the wrong man. She hadn’t registered any details about her attacker’s appearance during the incident itself, but she had looked at the picture she had taken. He seemed to be in his 20s or early 30s, and was wearing patched jeans, white sneakers and a black parka. He had a vacant gaze, a small, distinctive bump over his right eyebrow and a tiny scar over his left. If you looked closely, you could see a cigarette clutched in his left hand.

Detectives told her that despite the photographic and video evidence, her mistake would prevent them from taking anyone into custody. When I asked sources at the New York Police Department to explain why victim identification, known to be so unreliable, would trump visual imaging — which, in this instance, included a high-resolution iPhone photo taken immediately after the attack — a spokesman responded with an email that said: Detectives “work closely with District Attorney’s Offices to build the best possible prosecution,” which includes “taking several investigative steps” to “effectuate an arrest.”

In other words, no matter the clarity of the imaging, the human determination remained the gold standard, and in the absence of an accurate one, the case was considered too weak to move toward conviction.

This implicit understanding of living creatures as the most dependable witnesses to traumatic events contradicts decades of social science research. According to a report by the Innocence Project, titled “Re-evaluating Lineups: Why Witnesses Make Mistakes and How to Reduce the Chance of Misidentification,” empirical and peer-reviewed research “reaffirms what DNA exonerations have proven to be true: Human memory is fallible.” For all the downsides of living amid ever-present 21st-century surveillance, one benefit would presumably be the capacity to correct for exactly these errors of human observation.

Memory formation exists in three phases: encoding, storage and retrieval. “When someone is in a moment of stress — when someone has attacked them — that stress impacts both the encoding and storage functions,” Alexis Hoag-Fordjour, a criminal-law professor at Brooklyn Law School, explained. There is a frustrating lag, she said, between developments in technology, pathology, social science and science in general and what happens in the law.

There is not a uniform approach to using pictures and security camera footage when making decisions in criminal cases. “The irony,” Alex Vitale, a sociologist who has studied policing for 30 years, said, is that if Laura had died, the police “would have been perfectly happy” to arrest the suspect “in the absence of a positive eyewitness ID.”

Some lawyers, like Julie Rendelman, formerly the deputy bureau chief of the homicide division at the Brooklyn district attorney’s office, maintain that mistaken identifications should not necessarily prevent prosecution from moving forward, or, as she explained, “that the level of crime should be relevant to bringing the case.”

What happened to Laura was psychologically disruptive above all. The release of her assailant is the sort of outcome bound to enrage those who see New York as an increasingly dangerous place where law and order have been subjugated to the ostensible virtues of progressive reform. But it would also gnaw at progressives who view inadequate attention to the psychological well-being of homeless and other marginalized people as the problem animating our sense of unrest.

Detectives asked if she wanted to press charges, and she did — so that the man who attacked her, she reasoned, could get help.

Lincoln Restler, the City Council member who represents the area where the attack took place, said that the decision to prosecute an assault like this one “should be made by the D.A.’s office every single time,” adding: “If that case is taken up, then the courts, a judge, could refer the alleged assailant to treatment services, even housing,” assuming that is what is needed.

As Mr. Vitale suggested, “It is not as though we don’t know who these people are who are responsible for these quality-of-life problems.” The challenge, as he put it, is that “we don’t know what to do about them.”