I would work closely with LE, stressing that I wanted the truth to be found no matter what. I would ask LE to set me up with the very best FBI profilers, I'd provide them all info they wanted. I would research to find the best psychologist in the U.S. for working with sociopaths, meet with them, provide all info. I would pay for the psychologist to work with the FBI profilers, LE, all info they had, all info I (and family and friends) could provide them, to develop a set of questions I could ask my daughter.
I would ask the psychologist and the profilers to coach me on how to ask the questions, what tone of voice, what facial expressions, what body language I should use, IOW how to ask the questions to give the very best chance of getting more info from my daughter to find out what happened. For my own personal reasons, I would ask them to also help me determine *why* it happened.
It would be agony, but I would have to work to find out what happened.
I'd find out from the profilers and the psychologist whether my daughter would kill again, how much damage she would cause other people, and I would then work with LE, SA, and my daughter's attorney for LWOP if she would damage others. I believe every sociopath causes extensive damage to others, and can not by age 22 be helped not to, so I don't think I would try to get a reduced sentence. I'd just want her contained.
Then I'd visit her occasionally, write to her once a week, try to provide what she needed (not wanted). And I'd cry a lot and go into therapy and maybe go back to school for something to distract me from the hell I'd be living in.