A Mexican citizen handed over to the U.S. to face cartel-related charges died in federal custody three months later, after he was found hanging in his cell at the notorious MDC Brooklyn jail, the Daily News has learned — raising questions about how a man with a cellmate was hanging in his cell with nobody seeming to notice until it was too late.
Carlos Alberto Guerrero Mercado, 47, accused of cooking up fentanyl that ended up in the U.S. was found lifeless in his cell at about 1:20 p.m. April 18, and died in a hospital on April 28, after he “suffered a cardiac event,” according to a filing by federal prosecutors. Sources familiar with the case said his cellmate in the troubled Sunset Park jail found him hanging in his cell.
A “unit distress” alarm summoned staff to the cell, and correction officers found him on the ground, unconscious with no pulse, near two other inmates, the sources said. The officer attempted CPR and gave him two doses of the anti-overdose drug Narcan, then called fro EMS to get him to NYU Langone Hospital in Sunset Park, where he was kept on life support until his death, the sources said.
While an autopsy was conducted, his cause of death remains undetermined, pending a further investigation, sources said.
Guerrero Mercado’s lawyer, Kannan Sundaram of the Federal Defenders, said he wasn’t notified his client was hospitalized, and he didn’t learn anything was amiss until April 20, when Guerrero Mercado didn’t show up for a 2 p.m. video conference call. Sundaram’s investigator in the case got a call fro Guerrero Mercado’s wife about an hour later, saying jail staff told her he was unconscious and hooked up to a machine.
“Carlos Guerrero Mercado was a 47-year-old man with no criminal record who leaves behind his wife, his six-year-old son, and both of his parents,” Sundaram told The News. “People charged with crimes and presumed innocent should not be subjected to subpar conditions or fear dying in pretrial detention. Their families should not have to fear losing a loved one.”
“If the United States is going to just grab people from other countries with no legal process, while at the same time demanding that they be detained, our government should have a better and safer place to confine them than MDC Brooklyn,” he added.
MDC Brooklyn, which is notorious for its dire conditions and violence, houses alleged CEO-killer Luigi Mangione and ousted Venezuelan president Nicolas Maduro.
In 2024, the jail saw a string of violent attacks, including two murders over just six weeks, and a caught-on-video assault that showed a trio of MS-13 attackers stabbing a fellow gang member for 37 seconds before a lone correction officer arrived to stop them. The jail in recent years has seen an eight-day blackout during a polar vortex, constant lockdowns, a laundry list of medical mistreatment episodes and botched cancer diagnoses and inmate complaints of maggot-infested food.
It’s New York City’s only active federal jail, after the Metropolitan Correctional Center in Manhattan was shuttered in 2021, two years after sex fiend financier Jeffrey Epstein hanged himself there.
First death in 2026
Guerrero Mercado’s death marks the first in MDC Brooklyn custody this year, according to federal Bureau of Prison spokesman Emery Nelson. The jail didn’t see any deaths in 2025, and four in 2024, he said.
Nelson said the agency doesn’t determine or release causes of death, and wouldn’t say if any jail staff were under investigation or disciplined in the wake of Guerrero Mercado’s death.
“Based on the need to ensure safety and security in our institutions and in accordance with privacy concerns, we do not discuss potential allegations of staff misconduct or comment on matters that are the subject of legal proceedings,” said BOP spokesman Emery Nelson.
“Additionally, we do not confirm or deny whether a specific employee is currently on administrative leave or otherwise disciplined, nor do we confirm or deny the existence of a corresponding investigation.”
The BOP often sends press releases to members of the media about deaths in custody, but no such release went out for Guerrero Mercado’s death. Said Nelson, “While a press release was not issued for the death of Mr. Mercado, all proper notifications were made, as is the case in all inmate deaths who are in the custody of BOP.”
Lawyer Deirdre Von Dornum, who led the charge against horrific conditions at the MDC Brooklyn jail when she worked for the Federal Defenders, blasted the BOP for not being forthcoming.
“MDC operates in secrecy. The lack of transparency about the deaths of people like Mr. Guerrero Mercado, who are in the care of BOP, should be a cause of great concern,” she said. “How does someone with a cellmate commit suicide? Where were the officers who are supposed to be on every unit?”
Guerrero Mercado was one of 37 Mexican citizens shipped to the U.S. in January to face a variety of narcoterrorism and cartel-related charges — the third such transfer in less than a year. Guerrero Mercado and a second man were brought to Brooklyn Federal Court to face a 2024 indictment alleging they got the chemical building blocks of fentanyl from China, then turned those chemicals into “massive quantities of fentanyl” that were ultimately sold in the U.S.
A representative of the U.S. Attorney’s office in Brooklyn declined comment.
Despite speculation that the move was made as a gesture to appease President Trump, Mexico has been working more closely with the U.S. under President Claudia Scheinbaum and her Secretary of Security, Omar Garcia Harfush — a popular anti-cartel crusader known as Mexico’s “Batman,” noted Carin Zissis, Mexico analyst at Americas Society/Council of the Americas.
“The relationship between the United States and Mexico is so immense and huge, and there’s so many different challenging things going on in the relationship simultaneously, that it’s difficult to see this incident as being something that would be difficult in the relationship,” Zissis told The News, adding that the Mexican public has been suffering for decades from cartel violence.
Representatives of the Mexican consulate in New York did not return messages seeking comment.