The Investigator Fingerprints. Eyewitness accounts. Bite marks. All suspect? The L.A. public defender’s office decided it needed a scientist.

Erin Morris keeps a document on her computer with a rundown of subjects she has advised on in recent years. Sexsomnia (sexual behavior during sleep), machete-chop wounds, canine-scent detection, rape-trauma syndrome (how rape can affect a victim’s personality and behavior), pathological gambling, pediatric-onset bipolar disorder, crime-lab comparisons of duct tape and zip ties, the effects of pesticide use in the 1970s in South Korea, and the impact of gruesome photographs on jurors’ decision-making. That’s just a partial list. Morris is a behavioral-sciences research analyst for the Los Angeles County Public Defender’s Office, the first person to ever hold the job. In recent years, forensic and behavioral sciences have evolved so quickly that it’s impossible for most of the office’s approximately 700 lawyers to keep up. This is where Morris comes in. She is responsible for understanding the academic literature, determining which studies and theories are valid, and consulting with attorneys on how to pursue or challenge a line of inquiry. She raises questions a lawyer might not even know to ask. Morris is 39 and has freckled skin, blue-gray eyes, and a tendency to talk fast. A “closeted goth” in her youth, she maintains a large collection of skull art both in her home and in her office. A skeleton in a red bow tie and top hat with a word bubble that says cheers! hangs from a magnetic board in her cubicle, and a silver skull usually dangles from around her neck. She spends most of her days burrowing into case files filled with horror. “If you are a person with any drop of empathy, you break for a moment,” she says. “Your heart hurts for what someone went through.” But she also finds the cases intellectually interesting. “It’s a puzzle, knowing that no single piece is going to be the whole story. It’s not just necessarily what the client says happened or what the witness says happened. There can be multiple explanations.” That is what happened in the winter of 2013, when she received a file that pointed her to a problem she had never encountered. The case involved financial fraud and murder and had taken four years to reach a preliminary hearing. The victim, a 35-year-old art teacher at Markham Middle School in Watts named Alexander Merman, had been stabbed seven times in the back of his head and neck. In the crime-scene photos, he lay sprawled in a pool of blood on the floor of his Santa Monica condo. A blood-soaked towel partially covered his face, and blood had splattered bookshelves and an armchair. Merman’s financial adviser, Daniel Becerril, was accused of the murder, but none of his fingerprints or DNA had been found at the crime scene, and detectives never uncovered a murder weapon or any witnesses. Becerril had no record of violence. Becerril met Merman in 2004, after giving an investment presentation to a group of educators. Merman had received a large inheritance from his uncle and was looking for advice. Over the next few years, Becerril managed Merman’s money, and the two grew to be friends. After Merman was found murdered, police discovered that Becerril had been siphoning money from Merman’s bank account. Phone records showed that Merman had used his cell on the morning of Tuesday, March 18, 2008, but that after 12:40 p.m. all activity stopped. The next evening, a neighbor checked in on him and found his body and called 911. The chief of forensic medicine at the coroner’s office estimated the time of death to be between 12:46 p.m. on Tuesday and 2:46 a.m. on Wednesday — a 14-hour window. Becerril’s cellphone placed him in the vicinity of Merman’s condo just outside that window — at 12:40 p.m. Tuesday. By 1:04 p.m., around the time Merman stopped answering or receiving calls, Becerril’s cell pinged at a tower 1.5 miles away from the condo, and at 1:06 p.m., it pinged at Olympic Boulevard, 2.7 miles away. After that, his phone continued to ping into Orange County, approximately 50 miles away. The murder case against Becerril, Morris understood, hinged on the time of death. To determine when someone has died, medical investigators depend on a set of indicators that can include body rigidity, body temperature, decomposition, stomach contents. But in recent years some coroners have refused to give a time of death, believing it is impossible to establish accurately. She set out to investigate.

For more than 100 years, courtrooms across the United States have turned to forensic evidence to mete out justice. A lone fingerprint found at a crime scene could be sufficient to convict. A bite mark that matched a suspect’s teeth could result in a death sentence. A lead analysis could link a bullet to a crime scene and sway a jury toward a guilty verdict. But what once was considered incontrovertible is now under scrutiny. Since 1989, more than 340 defendants have been exonerated through DNA analysis; according to the Innocence Project, reviews of these cases revealed that faulty forensic evidence had convicted many of the defendants. “We wouldn’t want Ouija boards in court just because people have used them a lot and they thought they were helpful,” says Jennifer L. Mnookin, a dean of the UCLA School of Law and co-director of the Program on Understanding Law, Science, and Evidence. In September, the President’s Council of Advisors on Science and Technology released a report that questioned many of the methods used by law enforcement and prosecutors. Expert witnesses, the report explained, frequently overstate the accuracy of evidence, sometimes testifying that their findings are 100 percent certain, even when such claims “are not scientifically defensible.”

Many scientists now agree: Examiners’ unconscious biases can and do lead to false-positive fingerprint identifications. Bite marks cannot reliably implicate or exclude a person in a crime. And there is no basis for drawing a connection between the lead content of a bullet discovered at a crime scene and a particular box of ammunition. The use of scientific evidence in the criminal-justice system is experiencing its most radical shift in 25 years, which makes Erin Morris’s role crucial. She is the only all-purpose scientific researcher in a public defender’s office in the country. The youngest of three, Morris grew up in a suburb of Binghamton, New York. She was majoring in theater design at the University of Maryland, College Park, when she came across the work of cognitive neuroscientist Michael Gazzaniga, who was famous for his studies of split-brain patients, which helped explain false memory. She began reading the work of neurologist Oliver Sacks and eventually changed her major to psychology. She decided to pursue a Ph.D. at the University of California, Irvine, where she studied the intersection of psychology and law under Elizabeth Loftus, whose pioneering research contributed to the re-evaluation of eyewitness testimony. Another of Morris’s professors was William Thompson, who worked on wrongful conviction cases and often consulted for the L.A. public defender’s office. “Their deputies were just being overwhelmed by science and social-science evidence,” Thompson recalls. “They kept saying, ‘We wish we could have you or some of your students work with us all of the time.’” Thompson thought Morris was the ideal candidate if the office wanted to create the position. “She has this fascination with cases, and she really likes to get into the details,” he says. “She likes to break things down and figure out what the strengths and weaknesses are.” In her first month on the job, Morris was sitting next to a defendant at a trial when he lunged over and attacked his lawyer. She was soon thrown into legal questions about fetal alcohol spectrum disorder, child abuse, and animal torture. At one conference, she thought, I’m going to fucking lose it. She found herself bursting into tears out of nowhere, “like a puddle on the floor,” and decided to see a therapist, who helped her realize she was experiencing trauma by proxy. After a few sessions, Morris says she began to feel better. “I think it was really a matter of talking through it.” She realized it was OK to feel these emotions and then put them aside and fixate on the job. “You get hit by these things,” she says, “but then you just go back to the clinical thinking — what are the facts of the case, what does this evidence show?” By her own estimate, Morris has worked on more than 200 cases. There was the murder trial in which the defendant was accused of ritualistically murdering and dismembering his victims. The prosecutor claimed he was mimicking a vampire and brought in an expert witness whom Morris helped debunk. There was the case in which a woman had been charged with battery of a police officer. Morris researched whether nerve damage could cause her to spastically kick the officer after he torqued her arm behind her back. And there was the case that drew on the work she had done at Irvine. Police had arrested a young man for brutally assaulting a group of high school students. The fate of the defendant rested on a single eyewitness — one of the victims had later identified the man in a crowd at a basketball game. Morris was on top of the latest research on eyewitness testimony and advised the public defender of its many flaws — that head injuries, for example, often affect memory and that it’s easy to confuse two people who wear similar clothing. The jury handed down an acquittal.