How Did Jotaro Die?

Jotaro died in part six of the manga Stone Ocean. During one of Pucci's assaults where he tossed blades at Jolyne and Jotaro immediately halted time to forestall it. Jotaro now has two options, Save his girl.

Who killed Jotaro Kujo?

Dio attempts to kill Jotaro with one final kick, but a counterattack from Jotaro splits The World in two, killing it and Dio.

Does Jotaro die?

Despite the police and Holy telling him he was free to go, Jotaro insisted on staying, demonstrating the danger by taking one of the policeman's guns and shooting himself in the head. He was not killed, however, as a third arm appeared to him and was able to catch the bullet in mid-air.