Hello,  I am relatively new to meditation and am currently doing both insight and concentration practices daily.  My question is:  Is it possible to develop mental powers that would allow me the knowledge through second sight or something, to catch the person that brutally stabbed my sister to death?  My sister was 15 at the time and I was 17.  I am grown now but would like to know if this is somehow possible.  Thank you.

No, this isn't possible.  Meditation might bring you peace of mind, though, so still worth it, I'd say.

It may or may not also grant you insight into what existence is about, and thus what really happened. There's only one "Self" and the idea that there is a separate "you" or "me" is really just an illusion of the mind. In this context, accepting what happened will be easier. In essence, your sister was God like everyone else, and God killed herself by using another "person". It's a bit hard to grasp for the conditioned mind but the truth tends to reveal itself as self evident sooner or later.

IMO, everyone has such powers inside themselves, it's possible to allow them to come out, but few will be able to do that.  IMO, the power usually only surfaces if you are mentally ready.  That typically includes having dealt with past traumas, having an extremely stable and balanced personality, having a deep understanding of how both bad things and good things contribute in important ways to growth, etc.  Those kinds of power typically come with considerable personal development in all kinds of areas of self.  Also, how things pan out also depends on the development needs of all the parties involved.  As much as we may prefer only positive experiences, some things can only be learned via difficult experiences.  
-Eva 

Yes, this is my sense of the way these things work.  The desire to help a local family find their missing child has repeatedly arisen out of nowhere while I have been sitting recently.  I've heard such ablities might be accessible with discipline and certain practices but don't really know the specifics.  I only know that the wish to help both my won family and the family with the lost child persists.  I will say that I have no hatred or malice in this regard, I let that go and am past that. 

Circumstances don't allow for this.