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 phone 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 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 he helped plan and execute the Boston Marathon bombing a year ago today, 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 U.S. 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 Mr. 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 he gets cards and letters.
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 Mr. 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.
Mr. 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 defense 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.