Boston Marathon bombing suspect Dzhokhar Tsarnaev returned to court today for the first time since he was arraigned in July 2013 and his lawyer said the defence will ask to delay his upcoming trial.

Tsarnaev also received a shout of encouragement from the mother-in-law of a man who was shot and killed while being questioned by law enforcement after the bombings.

Defence attorney David Bruck told the judge that the defence plans to soon file a motion for a continuance.

He did not say how long of a delay the defence will seek.

Tsarnaev's trial is scheduled to begin with jury selection on January 5.

Security was tight at the federal courthouse in Boston for Tsarnaev's final pre-trial conference.

The judge made no rulings, saying he would rule in writing on pending motions, including the defence's latest push to move the trial out of Boston.

The mother-in-law of Ibragim Todashev shouted at Tsarnaev in Russian in the courtroom. Elena Teyer says she told him: "We prayed for you. Be strong, my son. We know you are innocent."

Later, in English, she yelled to the law enforcement officers escorting her out of the room: "Stop killing innocent people. Stop killing innocent boys."

Tsarnaev never flinched or acknowledged the shouts.

Three people were killed and more than 260 were injured when two bombs exploded near the finish line of the April 2013 marathon.

Tsarnaev, who has pleaded not guilty to 30 federal charges, faces the possibility of the death penalty if he is convicted.

The 21-year-old defendant wore a black sweater and grey trousers and had a scruffy beard and a mop-top hairstyle similar to the one seen in his mugshot. He smiled to his attorneys and one patted him on the arm.

The courtroom was packed with FBI agents, police who worked on the case and more than a dozen survivors and family members.

Tsarnaev's trial is expected to last several months, and seating a jury alone could take several weeks to a month.

Both sides have submitted questions they want the judge to ask potential jurors, who will be selected from a pool of at least 1,200 people.

Judge George O'Toole Jr. questioned Tsarnaev about whether he had waived his right to appear at previous hearings. Tsarnaev answered in a clear voice: "Yes, sir."

Asked by the judge if his lawyers had acted in his best interests, he said: "Very much."

A defence motion to move the trial out of Boston remains pending.

Earlier this month, Tsarnaev's lawyers argued anew that "emotionally-charged" media coverage and the widespread impact of the attacks have made it impossible for him to get a fair trial in Massachusetts.

O'Toole had rejected Tsarnaev's first request in September to move the trial, ruling that defence lawyers had failed to show that extensive pre-trial media coverage of the bombings had prejudiced the jury pool to the point that an impartial jury could not be chosen in Boston.

Tsarnaev's lawyers previously said the trial should be moved to Washington, DC.

O'Toole also rejected a defence request that prosecutors turn over evidence about his older brother's possible participation in a 2011 triple killing in suburban Waltham.

In May 2013, the FBI and Massachusetts State Police were questioning Todashev about that killing when an FBI agent shot and killed the 27-year-old mixed martial arts fighter inside his Orlando, Florida, home.

Officials initially said Todashev had lunged at a state trooper with a knife but later said it was a pole. Todashev's family has disputed that account.

Prosecutors have said Todashev told authorities Tamerlan Tsarnaev participated in the Waltham triple slaying in which the victims' bodies were found with their throats slit and their bodies sprinkled with marijuana.

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