World Bulletin / News Desk

Attorneys for the accused Boston Marathon bomber on Wednesday will ask a federal judge to give them until at least September 2015 to prepare for his trial on charges related to the largest mass-casualty attack on U.S. soil since 9/11.

Dzhokhar Tsarnaev, a 20-year-old native of Russia's restive Chechnya region who moved to the United States a decade ago, faces the possibility of execution if he is convicted of killing three people and injuring 264 with a pair of homemade pressure-cooker bombs in the April 15, 2013 attack as well as shooting dead a university police officer three days later.

Defense attorneys have said they need time to review massive amounts of evidence collected by the government's investigation into the bombing. They also may seek to challenge before U.S. District Judge George O'Toole the death penalty threat.

Last month, prosecutors said they would seek to have Tsarnaev put to death if he is convicted of charges including use of a weapon of mass destruction.

Tsarnaev, who is being held in a prison west of Boston, has pleaded not guilty to all charges. His attorneys have not yet said if they will seek to have his trial moved from U.S. District Court in Boston, just 2 miles (3.2 km) from the spot where the bombs ripped through a crowd of spectators at the race's crowded finish line.

The trial, which will draw intense international attention, will pit prosecutors from the office of U.S. Attorney Carmen Ortiz, who last year convicted gangster James "Whitey" Bulger, against a defense team including top Boston public defender Miriam Conrad and Judy Clarke, a death penalty defense specialist from California.

Tsarnaev and his 26-year-old brother, Tamerlan, are accused of planting the bombs, which killed three people.