London, England (CNN) -- A British man who strangled his wife in his sleep while dreaming that she was an intruder walked free from court Friday after the case against him was withdrawn, prosecutors said.
The UK's Crown Prosecution Service requested that the case against Brian Thomas, who killed wife Christine while they were on vacation in 2008, be dropped due to a "unique set of circumstances."
Thomas, 59, of Neath, South Wales, had been on trial for murder at Swansea Crown Court, with prosecutors seeking a verdict of not guilty by reason of insanity that would have resulted in psychiatric custody.
But they said a closer study of evidence led them to believe the defendant should be released without further action.
"We have duty to keep cases under continuous review, and following expert evidence from a psychiatrist it was suggested no useful purpose would be served by Mr Thomas being detained and treated in a psychiatric hospital," prosecutor Iwan Jenkins said in a statement.
Jenkins said that there had never been any doubt that Thomas caused his wife's death, but the prosecution accepted evidence from experts on sleep disorders that indicated he should not be convicted of murder or manslaughter.
"We therefore have offered no further evidence and asked the jury to return a simple verdict of not guilty."
The court erupted in shouts of "yes" as family members greeted the outcome with jubilation, according to the UK Press Association.
"The death of Christine Thomas was thoroughly investigated by Dyfed Powys Police. Investigations continued after Mr Thomas was charged and involved the instruction of experts in several fields," Jenkins said.
"I must emphasize that the circumstances of this case are almost unique in the UK and there have been fewer than 50 instances recorded worldwide. It is only because of highly sophisticated tests carried out by sleep experts that Mr Thomas's condition could be confirmed.
"Our thoughts remain with the family of Brian and Christine Thomas, who have remained dignified throughout this difficult time."
The brief trial, which opened Tuesday, heard that Thomas killed his wife while the pair were taking a camper van vacation in western Wales, PA reported.
One night, Thomas -- who experts said may have been suffering worsening dreams due to withdrawal from anti-depressants -- experienced a violent nightmare in which he attacked and fought an intruder and got him in a headlock, only to wake and find he had strangled his wife.
Dismissing the charges, High Court Judge Justice Davis described Thomas as a "decent man and devoted husband" who bore no responsibility for his wife's death, PA reported.
Thomas's brother Raymond Thomas said the family were "delighted" by the outcome, the news agency said.
"He has always been a loving husband and a family man," he said. " This was a tragic, tragic episode and we are all very emotional."