NEW ORLEANS — The apparent suicide of a 15-year-old boy in the New Orleans jail is the second such fatality since inmates were moved to a modern new facility in September 2015 — a move then touted as a major step toward curbing security problems at the notoriously dangerous lockup.

Orleans Parish Sheriff Marlin Gusman’s Office said in a news release Tuesday that a deputy found Jaquin Thomas unresponsive in his cell at 9:19 p.m. Monday. The release said Thomas had used a mattress cover to asphyxiate himself. The teen was pronounced dead at University Medical Center just after 10 p.m.

A coroner’s report was pending.

Thomas had been in jail since July, facing trial as an adult on charges of second-degree murder and aggravated battery.

The sheriff’s office said the results of their investigation will be submitted to the Orleans Parish District Attorney’s office for review. The office did not immediately respond to a request for an interview with Gary Maynard, the court-approved “compliance director” Gusman agreed to appoint this year to oversee reform efforts. Maynard officially began work Oct. 1.

Gusman, the city’s elected sheriff, has been under political and legal pressure for years over conditions at the jail. Earlier this year, inmate advocates, the U.S. Justice Department and the city of New Orleans, which funds the jail, called for a federal judge to appoint a “receiver” to take control of the jail from Gusman. They cited persistent inmate violence and Gusman’s slow progress in complying with broad court-ordered reforms.

Gusman avoided such a takeover by agreeing to cede management authority at the jail to a court-approved outsider. The appointment of Maynard, a former Maryland corrections official, was announced in August and approved by U.S. District Judge Lance Africk in September.

Gusman had had long said that the move of inmates from the decaying Orleans Parish Prison complex to the $150 million Orleans Justice Center, would improve safety at the jail. In March, inmate Cleveland Tumblin, 61, died at a hospital days after hanging himself in a shower at the new jail.

Court-approved monitors said inmates and guards remained in danger from violence at the new facility. And, last month, a former inmate — a transgender woman — said in a federal lawsuit she was raped by a male cellmate soon after being locked up at the newly opened jail in 2015.

Gusman has repeatedly blamed a lack of funding from Mayor Mitch Landrieu’s administration for problems in adequately staffing the jail. However, an attorney with an organization advocating for inmates was sharply critical of Gusman after Thomas’s death.

“The Sheriff has known for years that the kids in his custody are among the most vulnerable in the jail, in need of care and close supervision. Yet he has failed to keep them safe,” Emily Washington, of the Roderick & Solange MacArthur Justice Center, said in an emailed statement. “Jaquin’s death is the second completed suicide at OJC this year, and is the most recent tragedy to underscore the intolerable conditions at the jail.”