Who killed Tupac Shakur?

I know a lot of these posts are of people going missing and murders of none famous people but I want to start a case on who killed Tupac. It always gets me on who he was murdered by. Lots of people claim it was the Crips member he got into a fight with earlier and lots of people say it was The Notorious B.I.G who paid someone $10million to kill him. Does anyone else have any theories on who killed him?