Libby, 21, went missing in the early hours of February 1, following a night out with friends in Hull.
She was last seen at the junction of Haworth Street and Beverley Road.
Her body was found seven weeks later on March 20, in the Humber Estuary close to Spurn Point.
Relowicz, 25, is charged with the murder of Libby on February 1, in Hull.
He also faces a second charge of rape, also in relation to Libby between January 31 and February 1.
Relowicz, formerly of Raglan Street, Hull, appeared before Hull Crown Court on Thursday for a preliminary hearing.
No pleas were entered during the short hearing.
A provisional trial date has been set for June 2, 2020, before High Court Judge Mr Justice Goss at Sheffield Crown Court.
The trial is expected to last five weeks.
A further case management hearing will take place in March at a venue and date to be fixed where Relowicz will be asked to enter his pleas.
No application was made for bail and Relowicz was remanded into custody.