For a time, it seemed no one wanted to serve on the jury for the trial of accused Boston Marathon bomber Dzhokhar Tsarnaev.
One after another, men and women cited job commitments, destination weddings, an aversion to the death penalty, or a certainty of guilt as reasons to prevent them from sitting on a trial expected to last at least three months.
But after six days of vetting more than 80 potential jurors, attorneys were on the lookout for the opposite problem: Those who appear to be trying too hard to get on the panel that will weigh one of the most watched cases in Boston history.
In courtroom parlance, they are known as rogue or stealth jurors, people who lie or conceal their biases during the intense scrutiny that prospective jurors undergo. The rogues can undermine a criminal trial.
Some might be seeking the celebrity of being part of a high-profile event, perhaps wishing to later write a book or speak on television shows or at press conferences. Others may work to conceal a proprosecution or prodefense bias.
In the jury selection process in the Tsarnaev trial, which has gone more slowly than the judge expected, attorneys have appeared suspicious about some jurors who provided what seem to be perfectly neutral answers.
Last week, defense attorney David Bruck raised concerns over one potential juror who seemed to be trying to “make it seem like she is a complete blank slate.” The woman, who works in a hospital billing office, said she could easily serve on a trial lasting three months or more because she has “good staff.” She also said that she had been exposed to little media coverage of the bombing and had no firm feelings about the death penalty.
Bruck later turned to US District Court Judge George O’Toole and said in a skeptical tone, “There are a couple of jurors who seem eager to serve.”
Another juror who raised attorneys’ suspicions lived in Watertown during the manhunt for the bombing suspects, graduated from the University of Massachusetts Dartmouth — where Tsarnaev attended school, though she was not there at the same time — and has family members who served in the military overseas. Nonetheless, she insisted she could remain impartial.
“Are you sure?” Bruck asked, after a pause.
The defense team also on Friday discovered one potential juror who, when filling out the jury questionnaire, alleged scant use of social media and little bias, but who had actually posted what an attorney called an “obscene exaltation” on Twitter the day Tsarnaev was captured.
Because a jury must be unanimous in imposing the death penalty, prosecutors especially have to be on the lookout for would-be rogue jurors who quietly harbor opposition to capital punishment.
They have raised doubts about potential jurors’ alleged openness to imposing the death penalty. In questioning prospective jurors, the prosecutors repeatedly refer to it in more visceral terms, such as the killing of another human being that can’t be undone.
“Could you really do it?” prosecutors have begun to ask in the Tsarnaev case.
Attorneys have appeared suspicious about some jurors who provided what seem to be perfectly neutral answers.
But catching deception in words or body language, when averted eyes could either mean lying or deference, can be deeply challenging for the judge and lawyers.
“It can be impossible to read the tea leaves,” said Daniel Medwed, a Northeastern law professor who focuses on criminal law and wrongful convictions.
Legal specialists say jurors may not even be aware of their own emotional biases. For example, a juror who has deep aversions to capital punishment, perhaps even unconsciously, but likes to think of themselves as open minded, can sabotage the federal government’s death-penalty case.
George Vien, a former federal prosecutor in Boston, said he and his colleagues were allowed to graphically describe an execution during the jury selection process in the carjacking and murder trial of Gary Lee Sampson in 2003.
When one potential juror claimed to be open minded about the death penalty, prosecutors explained how a convict on death row is transferred to a room, strapped down, and then injected with a syringe filled with lethal chemicals, Vien said.
When the juror heard that description, and then looked at Sampson, she retreated from her earlier assertion that she could impose the death penalty.
“The truth broke through,” said Vien, now a lawyer with the Donnelly, Conroy and Gelhaar firm in Boston.
Sampson’s case offers another example of the difficulties of determining juror honesty. After Sampson pleaded guilty, a jury voted 12-0 for a death sentence, but US District Judge Mark L. Wolf vacated that sentence in 2011, after finding that one of the jurors lied on a questionnaire about her encounters with law enforcement. The judge said he would have excluded her from the jury had he known, and a federal appeals court upheld the decision.
Prosecutors decided to seek the death penalty again, and a new sentencing trial is now scheduled for September.
In the Tsarnaev case, the judge needs to find roughly 70 suitable jurors, and then he will let lawyers and prosecutors dismiss some for strategic reasons before he ends up with a final panel of 12 jurors and six alternates.
Vien said attorneys on both sides of the Tsarnaev case need to be alert to every possible deception by prospective jurors, though prosecutors — given the need for a unanimous verdict — have to be particularly alert for the juror who hides an aversion to the death penalty but “wants the celebrity of being the controversial juror.”
Medwed of Northeastern said a person’s strong desire to be on the Tsarnaev jury may not necessarily be a red flag. Sometimes people want to fulfill their civic duty in high-profile cases, he said.
One prospective juror in the bombing trial, who works in the restaurant business, on Friday said he would like to be on the jury, which he described as “a major thing.” When probed about his motivations, he said, “someone has to be part of this.”
Jeanne Kempthorne, a former federal prosecutor in Boston, and other legal specialists said figuring out a potential jurors’ motivations — and their objectivity — is a nearly impossible exercise in sociology, psychology, and personal intuition.
“Very often it’s a gut thing,” Kempthorne said.