Until Issei decided to asked Renee as his tutor in German and the later agree in exchange for money. Things went smoothly but Sagawa's fantasies got wilder and wilder, especially his fantasy about eating Renee. He decided to shoot Renee in the neck while she was reading him a German poem in his apartment. After it, Issei chopped Renee's body and eating it. After two days he started to smell a little not so good thing.
He decided to clean up by throwing the body somewhere, he started to chopped every part of the body of Renee and stuffed everything in two suitcases. Issei supposed to throw the body in a pond when he noticed there were people walking around and he left the suitcase and ran. After a few days French policemen was looking for the owner of the said suitcase but then they found out that Issei on that time was snacking on some left overs of human meat he had saved in the fridge.
Soon after that, he was locked up, and was interrogated by three psychiatrists. The specialists concluded that Sagawa had a few screws loose, and chances of curing him from his mental illness were slim to none. He was brought to the Henri Colin Institution, without trial. His dad, an influential man in Japan, managed to get him moved to Japan.
After being in prison for about 15 months, Issei Sagawa was released (thanks to his fathers money and influence, and the quirks of the French justice system). Yes, you read that right, after murdering and eating Renée Hartevelt, he was out and about after less than 5 years in prison.
Because of what he had done, he became famous and invited to some TV show appearances. He was called as 'The Godfather of Cannibalism'.
He has become an artist now, play small rolls in Japanese movies.