The young woman was seen near the nightclub in Glasgow where Miss Buckley spent the evening before she disappeared.
A major police search was launched when the 24-year-old student was reported missing by friends on Sunday, 12 April, after she failed to return from a night out in Glasgow’s west end.
Her body was found at High Craigton Farm on the north-western outskirts of the city following a four-day search.
Alexander Pacteau, 21, has appeared in court charged with her murder.
Police yesterday released a CCTV image of a young woman who was seen at about 12:30am on 12 April on Dumbarton Road near the Gallus pub and Sanctuary nightclub.
She walked along Church Street and got into a taxi on Byres Road, which drove off towards Great Western Road.
Police later said the woman had been traced.
Detective Superintendent Jim Kerr said: “Our extensive review of CCTV has identified this young lady near to the Sanctuary nightclub and the footage indicates that she may have information that could assist with our investigation.
“I must stress that she is in no way connected with the death of Karen but she may have information that could assist with the investigation.”
Pacteau is also accused of attempting to defeat the ends of justice.
He made no plea or declaration when he made his second appearance at Glasgow Sheriff Court in April and was remanded in custody.
Miss Buckley, a qualified nurse, moved to Scotland in February and was studying occupational therapy at Glasgow Caledonian University.
Her case touched many people in Scotland and Ireland, with a number of memorial services held in her honour.
Hundreds of people attended her funeral on 28 April in the Church of St Michael the Archangel, in her native Mourneabbey, near Mallow, Cork.