Who is Geli Raubal from Hitler and what is their importance?

Geli Raubal was the daughter of Hitler's half sister, Geli was often seen with Hitler and he afforded her time and attention that he was never willing to give up for anyone else. It seems that Hitler might have become dependent on Geli and when she wanted to leave the country, Hitler became controlling and made certain that she was always supervised. She was found dead in Hitler's apartment, killed by his gun. The Party said that she had accidentally killed herself while playing with the gun but Hitler's opponents put the blame on Hitler.