The incident is reported to have happened in the early hours of Sunday September 11 at an address in the Grattan Road area.
The victim, a woman in her fifties, is being supported by specially trained officers.
Det Supt Jim Dunkerley, of the Homicide and Major Enquiry Team, said: “We are continuing to learn more about the circumstances, but it is clear that the victim has come to some harm and we believe this has happened after she left a nightclub in Sackville Street.
“Our enquiries to date suggest these males may have more information about her movements after this and it is vital that we speak to them so our enquiries can continue.
Anyone who recognises either of the men in these images is asked to contact the Homicide and Major Enquiries Team on 101, quoting crime reference 13160392149, or report information anonymously to the independent charity Crimestoppers on 0800 555111.”