Boston Marathon bomber Dzhokhar Tsarnaev is shown in a courtroom sketch.

Condemned to die for his part in the 2013 Boston Marathon bombings, Dzhokhar Tsarnaev is likely to await his fate over the course of years, if not decades, locked up in grim prisons under extreme conditions while his lawyers appeal his sentence.

The US Bureau of Prisons has not yet decided where Tsarnaev will go, but he is likely end up in one of two high-security detention facilities, Colorado’s ADX or Indiana’s Terre Haute, according to US District Attorney for Massachusetts Carmen Ortiz.

First the judge will hold a hearing where he will formally pronounce the sentence, Ortiz said after a jury decided on Friday that Tsarnaev, 21, deserved the death penalty.

He will then pass into the custody of the Federal Bureau of Prisons, which will determine where he should be held.

ADX, formerly known as the U.S. Penitentiary Administrative Maximum Facility, is likely “the most punitive, rigid, prison in America,” as defence lawyer Judith Clarke put it during Tsarnaev’s trial, arguing for life in prison for her client.

Life at the Florence, Colorado, prison is so difficult that prosecutors had worried jurors would vote for it as the harsher of the two sentences available to them, death or life imprisonment without possibility of release.

Imprisonment at the US Penitentiary at Terre Haute would place Tsarnaev with other federal death row inmates and in the same complex where federal executions are carried out, said Robert Dunham, executive director of the Death Penalty Information Centre (DPIC).

Tsarnaev’s execution is neither imminent nor guaranteed

If ADX is known as the highest security prison for prisoners not sentenced to death, Terre Haute’s death row is “the most maximum security of maximum security,” Dunham said.

Tsarnaev’s death sentence, once confirmed at the hearing, would make him one of just 59 prisoners condemned to execution in US federal courts, according to the DPIC.

If the sentence is carried out, he would join a group of just three federal prisoners executed since 1988, when capital punishment by the US government was reinstated. In addition, 32 US states allow the death penalty for state crimes, according to the DPIC’s website.

But Tsarnaev’s execution is neither imminent nor guaranteed. It will likely take at least a decade for his lawyers to exhaust all of his appellate options, said Dunham, and anywhere during the process, a court may overturn the death sentence, Dunham said.