BOSTON — Sending Boston Marathon bomber Dzhokhar Tsarnaev to prison for the rest of his life would bring years of punishment and rob him of martyrdom, jurors were told Monday.

“We have seen more pain and more horror and more grief in this courtroom than any of you would have thought possible,” attorney David Bruck said as Tsarnaev’s defense team began what could be a two-week campaign to avoid the death penalty.

“No punishment could ever be equal to the terrible effects of this crime on the survivors and the victims’ families,” he said. “There is no evening of the scales. There is no point of trying to hurt him as he hurt because it can’t be done. All we can do, all you can do is make the best choice.”

Bruck told jurors there are only two punishments for them to choose from: death, or life in prison without any possibility of parole.

“We are asking you to punish Jahar by imprisoning him for the rest of his life.”

Showing the court a photo of the federal Supermax prison in Colorado, Bruck said:

“He goes here and he’s forgotten. No more spotlight, like the death penalty brings.

“No martyrdom. Just years and years of punishment, day after day, as he grows up to deal with the lonely struggle of dealing with what he did.”

Tsarnaev, 21, was convicted this month of all 30 counts against him; 17 of those counts carry the death penalty for the murders of four — Krystle Campbell, 29; Lingzi Lu, 23; Martin Richard, 8; and Sean Collier, 26.

In deciding whether the former college student is executed for his crimes or spends the rest of his days in a high-security federal prison, jurors must weigh the heinousness of his crime and the toll on his victims against so-called mitigating factors, such as his relative youth, mental health and family background, and whether or not he is remorseful.

He has shown no emotion as he sits in court, and he has avoided eye contact with maimed bombing survivors and relatives of the dead.

Last week, federal prosecutors presented three days of gut-wrenching victim impact testimony, including an array of images showing the victims as happy, active people and edited videos that added a soundtrack featuring a loud explosion, screams and panicked voices to the horrific bombing scene outside the Forum restaurant, where Richard and Lu died.

Lead defense attorney Judy Clarke — a nationally known death penalty opponent — has acknowledged that Tsarnaev and his brother, Tamerlan, set off the bombs and shot MIT campus cop Collier. But she is expected to build a narrative showing her client as a puppet of his dominant older brother.

Tamerlan Tsarnaev, who was 26, died in a gunbattle with Watertown, Massachusetts, police three days after the bombings.

Clarke’s colleague, Bruck, began that narrative in his opening statement by noting, “The man who conceived, planned and led this crime is beyond our power to punish. Only the 19-year-old younger brother who helped is left.”

Several members of Tsarnaev’s family arrived in Boston over the weekend, but the defense is closely guarding its witness list. The relatives, who are at an undisclosed location after being forced to leave a suburban hotel, apparently do not include his parents, who divorced and returned to Dagestan before the April 15, 2013, bombings.

Court filings indicate that the defense plans to call expert witness Janet Vogelsang, a sociologist, to explain Tsarnaev’s difficult upbringing as the overlooked child of immigrants — displaced Russian Muslims whose American dream failed.

Under federal law, the jury’s decision must be unanimous. A deadlocked jury would result in an automatic life sentence for Tsarnaev — which means the defense only needs to convince one juror to spare his life.

The Boston Globe reported over the weekend that fewer than 20% of those polled in Massachusetts favor the death penalty for Tsarnaev. The number is down substantially since the days after the bombings.

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