• Luigi Mangione is under monitoring in a 9-by-7-foot federal solitary-confinement cell in Brooklyn.
• On Monday, he may be moved to the same protective unit as Diddy and SBF, who are in the same jail.
• A prison consultant called his conditions "miserable."

Luigi Mangione is being held in a 9-by-7-foot solitary-confinement cell at the federal jail in Brooklyn that also houses the rap mogul Sean "Diddy" Combs and the cryptocurrency fraudster Sam Bankman-Fried, Business Insider has learned.

The trio could be living together in the same 15-man protective-custody unit as early as Monday, Sam Mangel, a prison consultant who has knowledge of Mangione's housing, said.

Federal prison records confirmed Friday morning that Mangione, Combs, and Bankman-Fried were at Brooklyn's Metropolitan Detention Center.

Mangione is set to remain in solitary until at least Monday in one of MDC's small cinderblock Special Housing Unit cells — in a unit also known as "the SHU" and "the hole," Mangel said.

He'll eat meals in his cell, and inmates in his situation are typically allowed out for one hour of recreation or showering a day. Guards are supposed to check on him every 15 minutes.

"Miserable, just miserable," Mangel said when asked to describe conditions in federal solitary-confinement cells.

"SHUs are notoriously loud. You have people in there for psychiatric issues, for disciplinary reasons, and for withdrawal" from drugs, he said, adding: "So it is the loudest place in the jail — people are banging on their doors at all hours of the night."

Mangione is being held without bail on death-penalty-eligible federal charges in the December 4 ambush fatal shooting of UnitedHealthcare CEO Brian Thompson. He has yet to be arraigned on New York charges of murder as an act of terror, which carries a top sentence of life without parole.

New, high-profile inmates are often monitored in solitary cells in the days before their units are assigned, said Mangel, who said he had been in communication with the defense team through Craig Rothfeld, a prison consultant.

Rothfeld, who was in the audience for Mangione's first federal court appearance on Thursday, declined to comment.

"It's a standard protocol," Mangel said. "This is especially true for a young man that, you know, might have some psychiatric concerns or his legal team or the BOP has concerns," he added, referring to the Federal Bureau of Prisons.

"Even though it's called the 'SHU,' it's not for disciplinary reasons. It's strictly for administrative reasons," Mangel said.

A Bureau of Prisons spokesperson declined to comment, saying: "For privacy, safety, and security reasons, we do not discuss the conditions of confinement for any individual including their housing assignments."

Karen Friedman Agnifilo told BI that neither she nor Marc Agnifilo, her cocounsel, had spoken to Mandel. They did not immediately comment on Mangione's jail conditions.

The husband-and-wife team's Manhattan firm, Agnifilo Intrater, also represents Combs, who is being held without bail while awaiting a trial scheduled for May 5 on federal sex-trafficking charges.

He has pleaded not guilty to the charges against him.

In representing Combs, the firm complained about conditions at MDC throughout three unsuccessful bail applications, arguing that there were frequent random lockdowns and that inmates were deprived of basic trial-preparation materials, such as folders and notebooks. Combs' attorney Marc Agnifilo called the conditions "horrific" in one court filing.

One former prosecutor described the federal jail as frequently too cold or too hot and crawling with cockroaches — basically, "hell on earth."

Mangione's solitary-confinement cell would be equipped with a metal bunk-style bed and a steel one-piece combination toilet and sink. If he's lucky, the cell has a small built-in writing desk.

"You're usually only allowed out for one hour a day, but it could be more restrictive due to staffing issues, where you're only allowed out three times a week to take a shower or walk in a small, enclosed area," Mangel said.

Mangione would also be allowed out of his cell for attorney calls and visits, Mangel said.

"The defendant is actually sitting in a cage during the call," he said. "It's like a fenced-in area that has a monitor, and it's behind plexiglass, and the defendant is able to talk and have an unmonitored legal call during that time, usually for one-hour blocks."

Defendants can find these calls canceled at the last minute "because there's lockdowns and staffing issues," Mangel said, adding: "You get everything arranged, and then we're on the call, waiting, and the defendant never shows up."

He said he expected Mangione would have better access to phones and visitors after he's moved to the jail's protective custody early next week.

Mangel said he had been a prison consultant for Bankman-Fried, who is serving a 25-year sentence for stealing $8 billion from customers of his FTX crypto exchange. Bankman-Fried has remained at MDC's protective custody unit since his arrest last year.

Mangione's next federal court date was set for January 18. As of Friday morning, a date had not been set for his Manhattan arraignment on state murder charges.

This story has been updated to include responses from the BOP and Mangione's attorney.