Lawyers for Boston Marathon bombing suspect Dzhokhar Tsarnaev  say federal prosecutors are withholding evidence they consider crucial to their defense of Tsarnaev in the death penalty case, including his family's testimony.

In a memo filed in court Thursday, Tsarnaev's lawyers say prosecutors have been "spotty and inconsistent" on turning over materials.

Tsarnaev's lawyers say prosecutors should turn over all of the material to assist Attorney General Eric Holder and possibly later a jury "to see Mr. Tsarnaev as a complete human being who should not be sentenced to death."

Tsarnaev is charged with using a weapon of mass destruction and a host of other charges in the April 15 bombing. Two bombs placed near the finish line killed three people and injured more than 260.