A team of Yale researchers was among the first to diagnose the mental illnesses that plagued Sandy Hook shooter Adam Lanza, according to police documents. Their proposed treatment plan was ultimately resisted by the shooter and his mother.

On Dec. 27, the Connecticut State Police released its final report on the investigation into the Dec. 14, 2012 shootings at Sandy Hook Elementary School that left 26 students and school staff dead. The report contained the names of Kathleen Koenig YSN ’88 and Robert King, both staff at the Child Study Center, who began to treat Lanza in 2006. Together, King and Koenig sought to devise a course of treatment that combined behavioral-based therapy and a prescription for Celexa, a common anti-depressant.

However, Lanza’s mother, Nancy Lanza, objected to the program — particularly the use of medication to treat her son — and discontinued her son’s treatment after only four visits to the center.

“Koenig received a phone call from Nancy Lanza which reported her son was ‘unable to raise his arm,’” a document in the State Police report reads. “Nancy Lanza was reporting her son was attributing this symptom to the medication … due to her son’s symptoms, he would be discontinuing use of the medication. Koenig attempted to convince Nancy Lanza that the medication was not causing any purported symptoms which Adam Lanza might be experiencing. However, Nancy Lanza was not receptive to Koenig’s reasoning.”

Koenig, King and other Child Study Center representatives declined requests for comment.

Documents show that Lanza was first seen at the Child Study Center on Oct. 24, 2006 for a three-hour psychiatric evaluation conducted with King. The family was subsequently referred to Koenig, a psychiatric nurse, for regular therapy appointments.

The initial visit was arranged by Lanza’s father, Peter, who told police that Adam “loved being a kid.” But by age 11, Peter reportedly noticed a shift in his son’s disposition, prompting him to approach King.

During the initial examination, King found Lanza to have a “profound” case of autism and concerning isolationist and antisocial tendencies. Still, King insisted to police that he saw nothing to indicate extreme potential for violence.

“During my brief meeting with [Adam Lanza], while I was concerned clinically with his rigidity and social constriction, I noted nothing … which would have made this unfortunate outcome foreseeable,” King told state police.

Koenig’s meetings with Lanza resulted in similar conclusions, resulting in her advice that he take medication. In particular, Koenig was hoping to treat Lanza’s case of OCD, which she believed “severely limited his ability to lead a normal, well-adjusted life,” according to the reports.

The disorder resulted in a number of odd behaviors, including washing his hands repeatedly, changing outfits numerous times throughout the day and wiping down surfaces with his sleeves before handling them. He also grew exceptionally sensitive to light, doctors noted.

Additionally, Koenig revealed to investigators that Lanza asked several questions about mental disorders during therapy without any apparent relevance to himself — he often framed his curiosity as general interest in schizophrenia, psychotic depression and OCD.

Koenig’s attempts and Nancy Lanza’s subsequent refusals bring to the forefront the difficulty mental health officials often face when working with uncooperative patients. Unless patients demonstrate that they pose a clear danger to themselves or others, professionals cannot compel treatment.

However, parents often resist prescribed courses of treatment, according to Howard Zonana, the director of the Psychiatry and Law Division at the Yale Medical School. Zonana said several factors could influence such a reaction, including denial or a belief that one’s case is simply not extreme enough to be treated by medicine.

Bandy Lee MED ’94 DIV ’95, a researcher at the School of Medicine who specializes in psychiatric violence studies, said that treatment is a critical step in keeping patients stable.

“When mental illness is well-treated in society, patients are not necessarily more violent,” Lee said. “But when they go untreated and they are allowed to become severely ill, then we’re seeing a larger share of violence being committed by mentally-ill individuals. That violence is different in nature, because it’s often unpredictable — it’s often based on delusions.”

In the case of Adam Lanza, who was living with his family and for whom there was no obvious cause to be brought to the hospital emergency room for psychiatric illness, no mechanism in place in Connecticut would have forced him to undergo treatment, according to Harold Schwartz, psychiatrist-in-chief at Hartford Hospital and a member of Gov. Dannel Malloy’s Sandy Hook Commission.

Because Connecticut is one of only eight states in the nation that does not allow involuntary outpatient treatment commitments, patients must first be involuntarily admitted to inpatient treatment, Schwartz said. A patient like Lanza would not have met that threshold for admittance, he added.

While Lanza was undoubtedly mentally ill, individuals with severe mental illness are more frequently victims of violence than its perpetrators, Schwartz said.

“The research is pretty clear that mentally ill individuals as a class are not significantly more violent than individuals without mental illness,” he said. “Regarding extremely serious acts of violence, only a small proportion is committed by people with severe mental illnesses.”

Between 1974 and 2000, 34 percent of all school shooters were at some point evaluated for mental illness, according to a report by the U.S. Secret Service.