Lawyers for Boston Marathon bombing suspect Dzohkhar Tsarnaev (joh-HAHR' tsahr-NEYE'-ehv) are asking to delay his trial until at least September 2015.

In a court filing Friday, the attorneys said his Nov. 3 trial date would give them about half the preparation time federal courts have allowed other defendants facing a death sentence over the past decade.

Tsarnaev is charged in the April 2013 attack that killed three people and wounded more than 260 others. He has pleaded not guilty to charges including terrorism.

The lawyers said they need more time to evaluate the "massive amount" of evidence, and to explore mitigating factors that could lesson his sentence if convicted.

The attorneys said at a hearing earlier this month they likely could not be ready for a November trial.