"I killed her."
But 35-year-old Clive Carter from Motherwell, said that he had no memory of battering Khanokporn Satjawat to death with a fire extinguisher in the ladies toilets in the Clyde Auditorium on November 12, last year.
However, he added that after talking with psychiatrists and psychologists about the incident he remembered hearing words in his head saying: "Die, just die."
Miss Satjawat was bludgeoned on the left side of her head with a fire extinguisher as she lay in a cubicle in the ladies toilets.
The force of the assault shattered all the bones on the left side of her face and smashed her skull.
The 42-year-old Thai national was in Glasgow to attend an HIV conference at the SECC.
Carter says that all he can remember of the incident is having a verbal argument with Miss Satjawat about her security pass and then sitting in the staff rest room eating his sandwiches.
He said: "I remember having a heated argument with her and then sitting downstairs having my sandwiches."
In evidence, at the High Court in Glasgow yesterday, the father-of-three told defence QC Ian Duguid that he had a row with Miss Satjawat when she asked why she should show her security pass.
Carter said he had gone up to the second floor after hearing a noise. He was heading back down towards the fire stairs when he saw Miss Satjawat.
He said she kept asking why she had to show him her security pass and this made him "angry, frustrated and annoyed."
Mr Duguid said: "Your emotions at the time were that she should just die, is that correct?" Carter replied: "Yes."
He added: "When I was asked about the incident by psychiatrists and psychologists I remembered the argument and I remember saying 'Die, just die' in my head. I didn't say it."
Carter told the jury: "I just basically asked do you have your badge. She said 'of course.'
"She started to get a bit angry about it. I wasn't sure what the problem was. She asked me why. I had a problem understanding what she was saying. Basically she was saying 'why do I have to show my badge?'
"She said: 'why is everyone having a go at me?' I said: 'I just have to see your badge.'
Carter said that after arguing for a couple of minutes Miss Satjawat pulled out her pass and waved it in his face.
After killing her, he went on his lunch break and was in the rest room when a colleague said there had been an incident in the ladies toilets. Carter said when he went up he saw Miss Satjawat lying dead in a cubicle he felt "shocked and dizzy" He added: "I was mortified by the sight of the lady in question."
Carter admits killing Miss Satjawat, but denies murdering her claiming diminished responsibility.
The trial continues.