Detained man is a 21-year-old company director with previous forgery conviction
The man detained by police in Glasgow is the same individual seen in nightclub CCTV footage talking to Karen Buckley late on Saturday night.
Alexander Pacteau is a 21-year-old company director, who has a previous conviction for forging banknotes.
On Tuesday, police had insisted Mr Pacteau is not a suspect in the disappearance of the Cork student but said he was helping them with their inquiries.
He had told detectives that Karen accompanied him back to his flat on Dorchester Avenue before leaving on foot at 4am on Sunday morning.
He insisted he offered to drive her home, however she declined the offer, and decided to walk home instead.
Mr Pacteau also told police Karen appeared to be okay when she left to go home.
However last night it emerged that Mr Pacteau had been detained by police in Glasgow.
Under Scottish law, when the police believe that someone has committed a crime, they can detain that person in custody for up to 12 hours.
This may be extended under certain circumstances, but at the end of the period the police must arrest or release the person.
Police also continued their examination of the flat, which has been sealed off since Tuesday.
Forensic teams were seen examining a garden at the rear of the property and nearby sheds.
Mr Pacteau's mother, Noreen (43), earlier spoke publicly to maintain her son is not involved in Karen's disappearance.
She told the Scottish 'Daily Record' newspaper: "She left his property at four o'clock in the morning and she was seen by other witnesses, not Alexander."
Mr Pacteau is director of a company involved in retail sales via mail order and the internet, and has been in this role since he was just 18.
Last year, he came to the notice of police following an investigation into forged currency.
Mr Pacteau pleaded guilty at Glasgow Sheriff's Court last year to forging banknotes worth £6,000.
He was caught by police before he had attempted to spend any of the forged notes.
The court was told that, as part of their investigation into Mr Pacteau, police found what was described as "equipment consistent with the production of counterfeit currency".
These included a laptop, a printer, ink cartridges and a paper trimmer, the court heard.
In his defence, Mr Pacteau's lawyer said he forged the banknotes as he was unable to find work following a serious car accident in 2011.
After the accident, Mr Pacteau was in an induced coma for weeks and was unable to walk for six months.
The lawyer said his client was embarrassed at having to sign on for state disability benefits and did not want to admit this to his family.
He also pointed out that Mr Pacteau had no previous convictions and came from a stable family and had a good education.
When he was just 17, he set up a business selling furniture online, the court was told.
Sheriff Sam Cathcart spared Mr Pacteau from jail and instead ordered the young man to carry out 225 hours of unpaid work.