I am an Indian National. Right now I am travelling USA for visiting purposes. In a couple of weeks I'll return to my home country but just now I heard from my friend in UK. She is facing a divorce case and needs me in UK as she wants to make me a witness in a court hearing. I have the solid evidence which will help her to win the case and otherwise she'll loose her kids and everything and she'll be on the road. So the situation is I have to go via UK on my way home.
Can I apply for a UK visa from USA?
If yes, then in which category do I have to apply?
And what documents do I need?