The city Department of Correction’s decision last year to place a 27-year-old transgender woman in solitary confinement at Rikers Island, where she died after suffering epileptic seizures, is not considered criminal, the Bronx District Attorney Darcel Clark announced late Friday.

Layleen Cubilette-Polanco’s death almost a year ago following epileptic seizures while in the jail’s solitary unit galvanized a movement calling attention to violence against Black and Latinx transgender people, especially in the prison system.

Polanco was being held on $500 bail due in part to a years-old prostitution charge. At the time of her death, she had been locked up at the Rose M. Singer women’s facility on Rikers Island for two months on an alleged misdemeanor assault in Harlem.

Polanco landed in solitary for 20 days after a fight with another inmate, according to a detailed profile in Out Magazine. Her family and advocates blamed the DOC for separating her from the general population, even though officials were aware of her medical history. Polanco reportedly had two seizures during her time in the jail. Her active seizure disorder should have been especially concerning because seizures are a relatively common cause of death in jail, the CITY reported, though a doctor reviewed her medical chart and cleared her for the solitary unit, according to records.

“The purview of this Office is not to determine whether it was a wrong decision to place Ms. Polanco into Punitive Segregation while she was suffering from a documented seizure disorder; the purview of this Office is to determine whether that decision rose to the level of criminal behavior,” Clark’s office wrote in a release about the investigation Friday. “After an in-depth investigation by my Public Integrity Bureau, we have concluded that we would be unable to prove beyond a reasonable doubt that any individual committed any crime associated with Ms. Polanco’s demise.”

Clark said her office conducted a six-month investigation and the ensuing report has been published online.

The city’s Department of Investigation said the probe uncovered problems with monitoring people inside the solitary units at mandated intervals. “Our investigation found no evidence of criminal wrongdoing, but DOI did find that City correction officers failed to follow the Department of Correction’s (DOC) directive that every inmate housed in Punitive Segregation shall be observed at least once every 15 minutes, at irregular intervals. In this case, they allowed 47 minutes to pass between tours of Ms. Polanco’s cell,” said DOI Commissioner Margaret Garnett in the release. “This violation was referred to DOC for appropriate administrative action.”

“We never believed the Bronx District Attorney would hold anyone criminally responsible for it,” Polanco’s family said in a statement to the New York Post through their lawyer David Shanies. “Layleen’s family has received amazing support from the community, but they have never relied on anyone but themselves, least of all the city government, to get justice for Layleen. In their pending federal lawsuit, they will hold Layleen’s killers to account.”

The New York Campaign for Alternatives to Isolated Confinement’s #HALTsolitary Campaign, which was launched after Polanco’s death, also issued a statement condemning the lack of accountability and calling for the end to solitary confinement.

“While we fundamentally believe the racist and transphobic criminal legal system will never be a source of justice or safety, we are nonetheless saddened and outraged by Bronx District Attorney Darcel Clark’s callous disregard for the life of Layleen Polanco. Both New York State and New York City must act immediately to bring justice for Layleen,” the statement said. “Facing sex work and drug charges, Layleen never should have been in jail, and both must be decriminalized. Furthermore, it is precisely because New York would lock a person with a dangerous seizure condition in solitary confinement that this medieval torture—this chamber of living death—must be abolished for everyone.”