Boston: He cannot mingle, speak or pray with other prisoners. His only visitors are his legal team, a mental health consultant and his immediate family, who apparently have seen him only rarely.

He may write only one letter — three pages, double-sided — and place one telephone call each week, and only to his family. If he reads newspapers and magazines, they have been stripped of classified ads and letters to the editor, which the government deems potential vehicles for coded messages. He watches no television, listens to no radio. He ventures outside infrequently, and only to a single small open space.

It has been nearly a year since police officers found Dzhokhar Tsarnaev in a suburban Boston backyard, hiding in a boat there, wounded by gunfire. Today he passes time in a secure federal medical facility, awaiting a November trial on charges that he helped plan and execute the Boston Marathon bombing a year ago on Tuesday, which killed three people and wounded at least 260, and a killing and kidnapping spree that forced an entire city into lockdown.

Now, at age 20, it is his turn to be effectively walled off from the outside world, imprisoned under so-called special administrative measures approved by the US attorney general. The restrictions are reserved for inmates considered to pose the greatest threat to others — even though, privately, federal officials say there is little of substance to suggest that Tsarnaev and his brother Tamerlan were anything but isolated, home-grown terrorists. A court order bars his legal advisers and family from disclosing anything he has told or written them.

Court documents and a snippet of a phone conversation with his family, released before the measures were imposed, offer glimpses into his life. Last May, he told his parents in Dagestan that “everything is good,” that he was eating meals of chicken and rice and that supporters had deposited some $1,000 (Dh3,670) in a bank account set up on his behalf.

And he gets cards and letters: at least a thousand so far, many, his lawyers have written, from people urging him to convert to Christianity. But there are others as well, from admirers and backers who believe he is innocent.

Crystel Clary, a single mother in Wisconsin who turns 35 on Tuesday, is one of them. She says she has written Tsarnaev 10 times beginning a month after the April 15 bombing, offering moral support and news titbits about such things as Eminem’s latest album and new movies. Prison authorities returned birthday and Valentine’s Day cards, she said, stating that she is not approved to write to Tsarnaev. Clary said that the letters have not been returned, and she has not received any replies from Tsarnaev. Her Twitter account nevertheless features photographs of Dzhokhar Tsarnaev and Tamerlan, who was killed by the police during a manhunt for the two men.

“You can tell he didn’t do it,” she said. “There is too much suspicious stuff going on in this case.”

In court documents, prosecutors appear to have amassed an arsenal of evidence from thousands of pages of documents and terabytes of digital information, including what they say is Tsarnaev’s hospital-bed confession and a call for others to wage holy war against Americans.

They are fodder for 30 criminal charges against him. Seventeen of them carry the death penalty. The federal court in Massachusetts, seldom accused of hurrying a case along, has given the two sides 19 months to prepare for a trial that the prosecution says could last three months.

Tsarnaev’s public-defender legal team — five attorneys, at least two investigators, a brace of paralegals and aides — has in turn called 19 months a “rocket schedule,” far too little time for the scorched-earth defence it appears to be assembling. They have filed repeated demands for sweeping access to prosecutors’ files and, according to prosecutors’ bitter complaint, ignored court rules requiring them to hand over considerably less information than the prosecution is being asked to give.

Defense lawyers have seized on even small incidents to cast the government as small-minded and vindictive, accusing prosecutors in court of twisting a joke by Tsarnaev about his confinement into evidence of his lack of remorse.

And both sides have waged legal war over the terms of Tsarnaev’s imprisonment, the special administrative measures that are both fairly standard for terrorist suspects and, the defence insists, unwarranted in Tsarnaev’s case. Special measures were first devised in 1996 but toughened and commonly imposed on accused terrorists after the attacks of Sept. 11, 2001.

Tsarnaev spends his days in Federal Medical Center in Devens, Massachusetts, a men-only prison hospital that houses 1,042 inmates and 131 others at an adjacent minimum-security camp. His health is unknown, although court documents hint that he has overcome at least the worst of injuries suffered during the manhunt that led to his capture last April.

The location and terms of his confinement are set by US marshals, and there is some leeway in the degree of isolation they impose: The administrative measures, for example, technically allow Tsarnaev to write one letter a month, but in practice he can send one a week.

Beyond being segregated from other prisoners — for their security and his, the government has stated — Tsarnaev may well spend little time outside his cell, period.

Richard Reid, the “shoe bomber” who sought to blow up an American Airlines flight from Paris to Miami in December 2001, was confined for 23 hours a day and given access to sunlight for an hour, according to Gerry Leone, a former US assistant district attorney and terrorism coordinator in Massachusetts who oversaw his case. As with Tsarnaev, he said, any communications to or by Reid were seized and scrutinised for hidden messages.

At their root, Leone said, the measures aim to prevent suspected terrorists from hatching more plots from their cells.

“Part of the reasoning is the tradecraft of terrorists, in that they recruit others,” he said. “They use many different forms of communications with others to try to compromise security.”

Prosecutors argue that Tsarnaev poses just such a threat: that he conspired to kill Americans, used Al Qaida’s bomb-making instructions as a blueprint, shows no remorse and could have still-unknown conspirators awaiting a coded call to action.

Shortly after his capture last April, “Tsarnaev reaffirmed his commitment to jihad and expressed hope that his actions would inspire others to engage in violent jihad,” the Justice Department stated in a court filing last August.

Defense lawyers assert in court filings, however, that prosecutors have offered no evidence that Tsarnaev is part of a foreign jihad network. Rather, the defence’s hiring of a mental health consultant may hint at an argument that he was mentally ill — and perhaps that he fell under the sway of his aggressive older brother, Tamerlan, a prospect they raised in court last month. Prosecutors asked the defence last Friday to disclose whether it plans to present evidence at the trial that Dzhokhar Tsarnaev suffered a mental ailment.

The American Civil Liberties Union opposes aspects of special administrative measures, and its Massachusetts branch unsuccessfully asked the court to hear its arguments.

“What brought us into the case was a concern about the right to counsel and the defence team’s ability to do its constitutionally mandated job,” Matthew R. Segal, the group’s Massachusetts legal director, said in an interview.

In the end, this may be what consumes Tsarnaev’s days — legal minutiae. Members of Tsarnaev’s legal team met with him on 80 of the first 162 days of his confinement, prosecutors said in a filing last October.