If headley was in pak, he would have been roaming around freely. As things stand, he is in jail. It's better that he stays in an American jail and not an Indian one, so that Indian taxpayers don't have to pay for his expenses. And by the way, Indian authorities have already interrogated him. And he is singing like a canary about Pakistan's terror camps, and the activities going on in the land of the pure. See the other thread about his revelations. He has revealed the role of the LeT, pakisani navy, Zarrar company of the SSG, and ISI, and their unholy nexus.
I wouldn't mention headley as a success story if I were you.