Pacteau, 21, who admitted attacking Ms Buckley in his car in April. pleaded guilty when he appeared at Glasgow high court.
The court heard how Pacteau met Ms Buckley outside Glasgow’s Sanctuary nightclub in the early hours of the morning and drove with her in his car to nearby Kelvin Way.
The car was parked on the street for 12 minutes, during which time Pacteau attacked and murdered her by grabbing her neck and delivering 12 or 13 blows with the spanner.
The court was told Ms Buckley suffered some injuries to her arm as she tried to defend herself. Pacteau’s silver Ford Focus was seen on CCTV leaving the area and heading towards Dawsholm Park, where the following morning a member of the public found Ms Buckley’s handbag near a bin.
A major search was launched for Ms Buckley, 24, from Cork, when she was reported missing from the flat she shared with friends after failing to return home from the nightclub in Glasgow’s west end.
Ms Buckley, a nurse who was studying for a post-graduate qualification at Glasgow Caledonian University, was seen on CCTV leaving the nightclub in the early hours of 12 April, and the footage captured her talking to a man as they walked together. Her body was found at a farm near Milngavie, ending a four-day police search.
Lord Advocate Frank Mulholland QC, prosecuting, told the court Pacteau had driven to his flat after the murder and put Ms Buckley’s body in his bedroom.
He used his phone to look up the properties of a chemical called sodium hydroxide, or caustic soda. He then locked his bedroom door and travelled to a DIY store, where he bought six litres of the chemical and masks and gloves, the court heard.
He texted his flatmate to make sure he was out for the day, then returned to the flat and left Ms Buckley’s body in the bath.
Pacteau was found cleaning the hall and stairwell when his flatmate returned home that night. He had moved her body into his locked bedroom wrapped in a duvet, the court heard.