For Hashi, who worked at a community youth organization in London, everything changed when he was approached by MI5, the U.K.’s domestic intelligence agency. He was pressured to become an informant, according to accounts he gave to rights groups and local authorities , but refused, despite being warned that doing so would make his life difficult.

Yet most of Hashi’s time in solitary confinement occurred before he had been deemed guilty by the justice system. Prolonged isolation prior to or in the absence of trial, sensory deprivation, and a lack of independent monitoring are normally associated with the detention center at Guantánamo Bay and CIA black sites overseas. But the MCC’s 10-South wing, which houses terrorism suspects, is no different in these respects. A former MCC prisoner and a psychologist specializing in trauma told The Intercept that the kind of extreme isolation imposed on defendants there can pressure them to accept a guilty plea, irrespective of actual guilt.

Mahdi Hashi, a young man of Somali origin who grew up in London, had never been to the United States before he was imprisoned in the 10-South wing of the Metropolitan Correctional Center in lower Manhattan in November 2012, when he was 23. For over three years, he has been confined to a small cell 23 hours a day without natural light, with an hour alone in a slightly larger indoor cage. He has had no physical contact with anyone. Apart from occasional visits by his lawyer, his human interaction has been limited to brief, transactional exchanges with guards and a monthly 30-minute phone call with his family.

BEFORE EVERY PHONE CALL that Fatuma Hashi has with her brother Mahdi, FBI agents come on the line to tell her what she is not permitted to talk about. “You’re not allowed to speak about political issues. Or whatever’s happening in the outside world. Or his case,” she told The Intercept.

In 2012, while Hashi was visiting Somalia, the British government used special powers to strip him of his citizenship, leaving him stateless. He crossed into neighboring Djibouti to visit the British consulate there, he claims, and appeal the decision. U.S. prosecutors allege he was traveling to Yemen to join al Qaeda.

Upon entering Djibouti, Hashi was arrested by agents of the secret police and forced to watch other prisoners gagged, blindfolded, and beaten for hours, he alleges in case filings, with the complicity of FBI agents and other unidentified Americans. According to defense attorneys, Hashi was threatened with physical abuse and rape if he did not cooperate.

In November 2012, he was transported to New York by the U.S. government to face charges of supporting al Shabaab, the Somali terrorist organization. Prosecutors say he traveled to Somalia to attend a training camp and fight with al Shabaab in Somalia’s civil war. They accept that Hashi poses no specific threat to any Americans and that he received “harsh treatment” in Djibouti.

In May 2015, after two-and-a-half years of isolation, Hashi entered a guilty plea of conspiring to provide material support to al Shabaab. Last week, on January 29, he was sentenced to nine years in prison. He will likely be incarcerated at a Supermax facility in Colorado or a high-security “communications management unit” in Illinois or Indiana, all of which mean ongoing solitary confinement.

Government prosecutors were seeking 15 years, but Judge John Gleeson of the Eastern District of New York said the case was “complicated,” and accepted, in part, Hashi’s position that he joined al Shabaab not to engage in violent attacks but because he thought the group could restore peace to war-torn Somalia. “I believe you believe this organization you joined was dramatically different than what you thought or hoped it would be,” Judge Gleeson said.

For Fatuma Hashi, the U.S. government’s approach is hard to understand. “He was in his own country,” she said. “It had nothing to do with the United States. Why does this country that has nothing to do with us have a say in his life?”

Fatuma cannot fully share with journalists what she knows about her brother’s treatment in the MCC, a gray slab of a building that goes largely unnoticed by the office workers and tourists walking the streets near the Manhattan end of the Brooklyn bridge. Government restrictions — known as “special administrative measures,” or SAMs — prevent prisoners, their attorneys, and family members from describing the conditions inside the high-security unit to the wider public, shrouding New York’s little Guantánamo in secrecy.

Psychological damage

In an account to be published in a new book on solitary confinement — titled Hell Is a Very Small Place — a Pakistani prisoner, Uzair Paracha, gives one of the most detailed illustrations yet of incarceration at the MCC. He was held in isolation there for two-and-a-half years after he was arrested in 2003 at age 23.

“The windows were huge but the glass was frosted so we had a lot of light but couldn’t see a thing,” he said. “It was a shade of white during the day, blue in the evening and early morning, black at night, and yellow when it snowed, as the snow reflected the streetlights. This was one way to estimate the time since they didn’t allow any watches.”

Video cameras constantly monitored the inside of Paracha’s cell, including the shower and toilet areas. Lighting was completely controlled from the outside, so that guards could deliberately leave the lights on at night to make sleeping harder. With their metallic walls, the cells were like ovens in the summer and freezing in the winter.

The medical effects of Paracha’s imprisonment at the MCC were severe: a weakening of his eyesight, brought about by having his entire world just a few feet away; a deterioration of physical coordination that made walking on stairs harder; and breathing problems, especially while trying to sleep.

Dr. Kate Porterfield is a clinical psychologist at the Bellevue/New York University Program for Survivors of Torture. She has evaluated prisoners held at various sites in America’s war on terror, including at Guantánamo. “With isolation, there’s a severing of the orienting data of our lives — the stuff that makes us feel like we are on our feet,” she told The Intercept. “This can result in paranoia, disorientation, feeling confused about whether your perceptions match reality, and not being sure who to trust.”

“That’s very dangerous to someone’s psyche,” she added. “It’s not just about feeling depressed because you’re in prison. The defendant ought to be oriented enough in the realities of their life and world that they can contribute to their own defense. A sense of paranoia and suspicion hampers the defendant in trying to connect with his or her legal team so that they can discuss and investigate the case.”

If a person has experienced torture or coercive interrogation before being put in isolation, they are even more vulnerable, Dr. Porterfield said. “There is then a greater likelihood of psychological damage and even less chance for recovery in any real sense.”

Indeed, virtually every academic study has concluded that solitary confinement has serious mental health consequences. These begin after 60 days and resemble the acute reactions suffered by torture and trauma victims.

The average length of time that defendants in federal terrorism prosecutions spend in solitary confinement prior to trial is 22 months, according to a 2014 report by Human Rights Watch and the Columbia Law School Human Rights Institute. Amnesty International has stated that pre-trial solitary confinement at the MCC amounts to “cruel, inhuman, or degrading treatment.”

At least one prisoner who has been held at both the MCC and Guantánamo has described the Manhattan jail as harsher. Ahmed Khalfan Ghailani, who was convicted of involvement in the 1998 bombings of two U.S. embassies in East Africa, told his psychiatrist that Guantánamo is “more pleasant” and “more relaxed” than the isolation section at the MCC. At Guantánamo, he said, prisoners were not strip-searched and could associate together for recreational activities.

Joshua Dratel, an attorney who has represented clients at Guantánamo as well as the MCC, has also said the New York jail is worse.

A tool for prosecutors

The one advantage that prisoners at the MCC are supposed to have over their counterparts in Guantánamo is that they are subject to trial in a criminal court rather than a military tribunal. However, the use of pre-trial solitary confinement has become, in effect if not intent, a tool for prosecutors to skew the judicial process in their favor.

Experts like Dr. Porterfield emphasize how extreme isolation can induce a desire to accept a plea. “We find again and again that isolation in prisons and the experience of maltreatment have a huge impact to the point where people do almost anything to get out of the coercive situation,” she said. “If there’s one thing the last 14 years have shown us, it’s that abuse does not lead to good information gathering.”

Laura Whitehorn was held for two months in pre-trial isolation at the MCC in 1986 on allegations of passport fraud, part of a larger conspiracy case for which she was later sentenced to 23 years in prison. “The sense of isolation, even after only two months, was so intense,” she told The Intercept. “I think, at that point, one would be ready to do almost anything to be back in human contact.”

“What was particularly horrible was the constant watching and monitoring,” Whitehorn recalled. “It was like being played with by the guards, a form of psychological taunting. I felt at any moment I could have any part of my being or body violated with impunity.”

Peter Quijano has represented several clients facing federal terrorism charges at the MCC, most of whom have been held in the jail’s isolation unit.

“It just seems obvious that if anyone, regardless of the mental state they have going in, is housed and detained in such a manner for any period of time, it has to start having an effect on them,” he said. “Anecdotally, we’ve seen increased deterioration over a period of time, especially in a pre-trial situation. It seems like a punishment and it affects their ability to assist in their defense.”

Legal visits at the MCC are hampered by the extreme temperatures in the “claustrophobic” visiting room. “It’s hard to stay there for much more than two hours,” Quijano said. Attorney and client remain in separate cages during the visits, divided by a mesh grate that makes eye contact impossible.

Severe restrictions on communication

Mahdi Hashi divides his monthly phone call between his parents and siblings in London and his wife in Somalia. His sister Fatuma described being “overwhelmed with emotions” on these calls after not hearing his voice for so long. “Every day I’m in pain thinking about his situation,” she said. Fatuma, who is 24, has not seen Mahdi for six years.

She says the family has sent him books that took eight months to arrive. He never receives the letters and photographs they send. But there are strict limits on what Fatuma can say publicly about his imprisonment due to the SAMs applied in his case, which prevent Mahdi Hashi from any “oral, written, or recorded communications” with another prisoner; restrict his monthly phone calls to immediate family members; and prevent his family from sharing the content of the calls with anyone else.

Nor is Hashi allowed to communicate with journalists in any way, including via his attorney. SAMs, which are issued by the attorney general, are supposed to be specific to individual prisoners who pose “a substantial risk” of communicating messages that “could result in death or serious bodily injury to persons.”

One consequence of the SAMs is that protests by prisoners remain hidden from public view. In September 2013, a blogger claimed that Hashi was on hunger strike to protest the conditions of his imprisonment. He was reportedly hospitalized with jaundice and close to liver failure. But the protest could not be verified or discussed in more detail.

“It’s a last resort when you have so few resources to defend yourself,” said Whitehorn, the former MCC prisoner, on reports of Hashi’s hunger strike.

It has not been established whether Hashi was forced to undergo the brutal force-feeding practices used at Guantánamo, although force-feeding was applied in response to the protest of another MCC prisoner. Oussama Kassir, a Swede who went on hunger strike at the MCC eight years ago, was subjected to “medical feeding,” according to his attorney.

The people best placed to shed light on Hashi’s hunger strike — his lawyers and his family — were restricted by the SAMs, and prosecutors and prison administrators declined to comment. According to the blogger, the FBI cut off a phone call from Hashi to his father — in which Hashi described the protest — after one minute, but the SAMs mean we cannot know if this actually happened.

Saghir Hussain, Hashi’s British lawyer, has spoken with his client about the conditions of his incarceration, but is prevented from sharing such information. Hashi’s American lawyer did not respond to multiple requests for comment.

Mahdi Hashi’s prosecution provides one model of how the U.S. government deals with Western citizens accused of fighting with jihadi organizations overseas: coercive interrogation outside of U.S. jurisdiction, transportation to the isolation unit of a federal jail in New York, solitary confinement and restricted communication in conditions of secrecy until a guilty plea is made, then a lengthy incarceration at a high-security prison.

From one perspective, this approach seems to respect the rule of law. But look a little closer and it becomes clear that there are possibilities for abuse equivalent to or worse than at Guantánamo.

Top photo: Razor wire hangs on a railing at the Metropolitan Correctional Center, June 9, 2009, in New York City.