An American citizen left a fellow student temporarily blind and in hospital after poisoning his drink with a solvent used in paint and anti-freeze, a court has heard.
Alexander Hilton, now 24, spiked a bottle of red wine with methanol and encouraged fellow US national Robert Forbes to drink it on the evening of a ball for students of St Andrews University in Fife.
Mr Forbes, also now 24, later experienced extreme lethargy, headaches, confusion and the complete loss of his vision for a time after consuming the toxic drink on March 5 2011.
Without treatment, the poison in Mr Forbes' system would have had "life-threatening consequences", the High Court in Edinburgh heard.
The court heard how the victim was given whisky as part of his treatment in hospital to help counter the effects of the toxin.
Hilton will be sentenced next month after today admitting a charge of assaulting Mr Forbes to his severe injury, permanent impairment and to the danger of his life.
He appeared before the court - more than four years on from the crime - after being extradited from the US on May 7 this year.
Judge Lord Burns told Hilton his crime was one of the "utmost seriousness" as he deferred sentencing until July 17.
The court heard that Hilton was in his second year studying economics and computing at St Andrews at the time of the incident. Mr Forbes, described as a "sociable young man", was a year below, studying economics, history and philosophy.
They were both part of the same large social group, living at the university's New Hall halls of residence.
Hilton, from Princeton, near Boston in Massachusetts, left St Andrews and the country shortly after the incident.
The court heard that , on the evening of Saturday March 5 2011, a student ball was being held in the Fife town for the New Hall students.
Mr Forbes began the evening having drinks with his friends in his room and was later joined by Hilton.
Prosecutor Alex Prentice QC told the court: "The accused brought two bottles of red wine with him. He handed one of the bottles of wine to Robert Forbes, stating that it was a gift.
"The accused had mixed the wine in this bottle with methanol. At this time, Robert Forbes noticed that the bottle of wine was full, but that the seal on the screw top was broken as if it had already been opened.
"During the time that the friends were within Robert Forbes' room, the accused kept encouraging Robert Forbes to consume the bottle of wine that he had handed him."
Everyone else in the room noted how "keen" Hilton was for Mr Forbes to drink the wine, the court heard.
Mr Forbes took two large gulps of the drink and found it had a bitter taste. He later drank more but continued to comment on how "foul tasting" it was.
He then started feeling unwell and sick and fell asleep on the bus to the function, the court heard. His recollection of the rest of the night is "very hazy".
The victim slept for much of the following day, eventually waking on Sunday evening with a severe headache, joint pain and blurred vision. Two days on from that, his sight "deteriorated significantly and he was struggling to see".
Mr Forbes was admitted to Ninewells Hospital in Dundee on March 8 that year, where tests showed he was suffering from the effects of methanol poisoning.
Mr Prentice told the court: "He was then admitted to the renal ward of Ninewells Hospital and was placed under the care of a consultant neurologist. He was then given haemodialysis alcohol treatment in the form of whisky, which stops the methanol being metabolised into its toxic state.
"Robert Forbes required to remain within Ninewells Hospital, Dundee, as an inpatient for another full week in order to receive the necessary treatment."
Hilton was interviewed under caution later that week, where he denied knowing that Mr Forbes had been poisoned and repeatedly denied having spiked the wine.
Police found that Hilton had accessed web pages on methanol poisoning, after the incident but two days before Mr Forbes' condition was diagnosed.
The court heard that methanol is used commercially as a solvent, especially in paints and varnishes, and is a constituent of some antifreeze solutions.
The court heard how the victim suffered from extreme lethargy, headaches, confusion and blurred vision, deteriorating into a complete loss of vision for a time.
He needed treatment to prevent permanent kidney damage.
"It would appear that Robert suffered no lasting damage to his kidneys. The same cannot be said for his vision," said Mr Prentice, who outlined a series of problems the victim continues to experience with his eyes and sight.
However, he now has his driving licence back and is expected to graduate from St Andrews next week.
John Scott, defending, told the court the case was "very unusual as well as being serious".
Hilton is on a "cocktail of drugs" to help him cope with his longstanding mental health problems, he told the court.
Mr Scott spoke of a "psychiatric background" extending back to before the incident.
He added that, unusually for a High Court case, he would be making the case at the next hearing for Hilton to receive a non-custodial sentence, describing the accused's circumstances as unusual and unique.
Judge Lord Burns deferred sentence for the preparation of a criminal justice social work report.
He told Hilton: "The crime to which you have pleaded guilty is of course of the utmost seriousness and will attract a custodial sentence in the absence of exceptional circumstances."