Yesterday morning police issued an appeal for information on the woman, seen on CCTV outside the Sanctuary nightclub in Glasgow that Ms Buckley visited with her friends the night she went missing.
The request received an immediate response, and Police Scotland has since confirmed that they traced the woman yesterday afternoon.
The potential witness was described as between 18 and 25 years old with long brown straight hair. She was wearing a short pink coloured dress and a fur jacket and was carrying a large brown shoulder bag on the night Ms Buckley went missing.
The woman was seen on Dumbarton Rd near to the Gallus Pub before walking along Church St at around 12.30am on April 12. She then got into a Hackney taxi on Byres Rd which drove off towards Great Western Rd.
Det Supt Jim Kerr said that an extensive review of CCTV footage has indicated that she may have information that could assist with their 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,” he said.
A qualified nurse, Ms Buckley was studying at Glasgow Caledonian University for a masters degree in occupational health therapy when she went missing after a night out in the city on April 12.
Ms Buckley’s disappearance sparked a massive search of a number of locations across Glasgow.
Ms Buckley was seen on CCTV leaving the Sanctuary nightclub with 21-year-old Alexander Pacteau, a director of a courier firm who lived in an apartment on Dorchester Avenue in the North West of Glasgow city.
He had claimed that Ms Buckley went back to his apartment and then decided to walk home at approximately 4am that morning. Her handbag was later found in a bin at the nearby Dalsholm Park.
Her body was found at a farm north of the city four days after her disappearance and Pacteau was arrested and charged with her murder.
Thousands of mourners attended Ms Buckley’s removal in Mallow on April 27, and her funeral in her native Mourneabbey the next day.