Before she was killed, slain dentist Preethi Reddy had met with her former boyfriend and told him she was planning to move interstate to be with her new partner.

A source close to the investigation said she was "so happy" and "so in love" with the Melbourne man she had started a long-distance relationship with in the wake of her break-up with Tamworth dentist Harshwardhan Narde.

Preethi Reddy was apprehensive about attending the same conference as her ex-boyfriend on Saturday.

Investigators believe that Dr Reddy went to her former boyfriend's room at the Swissotel on Market Street in the early hours of Sunday to tell him the relationship was done.

They are now looking at whether she was killed inside the room, her remains then stuffed into a suitcase and dumped in a car by the side of the road before Dr Narde drove into a semi-trailer and died.