Relatives of Boniface Umale, who died on remand in Durham prison, are unhappy with the official explanation.
The Nigerian-born student was found unconscious in his cell on Sunday 24 March this year.
The prison says that staff attempted CPR, but he was “non responsive”.
Newcastle Crown Court says he committed suicide.
The prisons ombudsman has launched an investigation into the death.
Boniface’s trial on charges of sexual assault and rape had finished and sentence was due on 25 March.
Daniel Okpla, a spokesperson for the Idoma community to which Umale belonged, accused Durham prison of “sweeping this matter under the carpet”.