Robert Lee Sutton carried out the terrifying knifepoint attack at the sheltered accommodation where he was living.
He fled leaving a note in his room saying "catch me if you can, ha, ha". He was arrested smoking cannabis some days later after he broke into a holiday caravan.
Mold Crown Court heard yesterday that Sutton was jailed for nine years in May 2004 for a robbery at a post office near Llangollen and four years in 2001 for an earlier robbery at the same premises.
He was back at the same court yesterday where he received an indefinite hospital order under the Mental Health Act and he will be detained at Ashworth Hospital, a high-security psychiatric hospital in Liverpool.
Sutton, who carried out the robbery while living at the accommodation in Newtown, admitted robbery, false imprisonment, two charges of criminal damage and possessing cannabis following the latest incident in March of last year.
He was made the subject of a restriction order which means he can only be released if it is approved by the Secretary of State or at a mental health tribunal.
Prosecuting barrister Mr Paulinus Barnes said that Sutton, 36, was living at the supported living scheme at Plas Canol in Newtown and on March 15 went into the office with a female support worker to get his medication.
She immediately felt uneasy where he started looking at the safe, she said the other staff always changed the code without telling her hoping that would dissuade him from doing anything.
But he said that was no problem, told her he was not going to hurt her "because she was practically family" but bound and gagged her, face down, on a bed with her arms behind her back.
She was terrified and told him she had asthma – but he said he would ring the police in about an hour to tell them what he had done.
He produced a kitchen knife with a large blade, put tape over her mouth after tying her hands with wire and her legs with tape, and he got away with £588, the court was told.
After he left she was able to free herself, locked herself in a bathroom and alerted the police on her mobile phone.
She was bruised from being tied up, her asthma had become worse and she had been left feeling scared and in a panic.
John Hedgecoe, for Sutton, said his client admitted what he had done in interview, pleaded guilty at an early stage, and the delay had been in the preparation of detailed medical reports.
Judge Rhys Rowlands said that he was satisfied on the medical evidence that Sutton suffered from paranoid schizophrenia, post traumatic stress disorder and had an anti-social personality disorder.