What happened in room 100 at Chelsea Hotel? The death of Nancy Spungen and Sid Vicious

11am on October 12. 1978. The Police got a phone call from a young man who said that he had found his girlfriend dead in their bathroom. The young man was Sid Vicious, the girlfriend Nancy Spungen and the bathroom was in apartment 100 in Chelsea Hotel on West 23rd street in New York.

When the police arrived they found Nancy Spungen in a pool of blood. She was wearing a bra and black lace panties, she was lying against the bathroom wall. She had knife wounds in her stomach.
How did all this happened?