Typically the Assistant District Attorney in Harris County who handled her case. My worry is that this ADA may no longer be there, or not as eager to sign the form and support her since its been 8 years. Harris County has become somewhat lackluster in supporting Form I-918 (U) visas unfortunately for no explicable reason since the last 1 1/2 years. Further, usually prosecutors are very eager to solicit the assistance of victims on cases they are working on but once the case is closed they may not be as eager or prompt to respond. Notwithstanding, I would still give it a try and wish you good luck. By the way, the Houston YMCA (Westpark) or Catholic Charities (downtown) often provide pro bono (free) or very low fee assistance for someone like your friend. Good luck.