It sounds like this Judy Clarke is the government's "fixer" to get patsies to plead guilty. This is the only way for the FBI to get out of proving they really did have a video showing the planting of the bomb.

Were Clarke really working for Tsarnaev, she could win the case simply by showing the jury the remains of the bomb and backpack, and the photos of both Tsarnaev brothers taken at the scene before the blast, which clearly show the brothers were not the source of the backpack with the bomb!

At top, the remains of the bomb backpack. Note the black color and white square patch. At bottom, the Tsarnaev brothers are on the left, the "Khaki" man with the backback identical to the bomb backpack is on the right.

When Martin Luther King was assassinated, Patsy James Earl Ray was told by his government-appointed attorney that if he did not challenge the official story and pled guilty, Ray would get a short prison sentence. Of course, the judge sentenced James Earl Ray to life without parole then refused to allow Ray to change his plea! I suspect the same thing is happening here. Clarke has likely told Dzhokhar Tsarnaev that if he pleads guilty and says his brother made him do it, he will get a light sentence. And Dzhokhar Tsarnaev won't know how badly he is being screwed until it is too late.