A theory that the so-called Piano Man could be Czech musician Tomas Strnad has been discounted - as Mr Strnad has been interviewed on Czech TV.
The unidentified man was found in a soaking wet suit
Mr Strnad confirmed on screen he was not the mystery character found wandering streets in Kent in April.
The theory had been put forward by Michael Kocab, who thought he had played in a band with the pianist he had seen on news reports from the UK.
Mr Kocab now says his theory that Mr Strnad is the Piano Man was a mistake.
Mr Strnad lives in Prague and has never been to England.
He told the Czech TV station CT24TV: "I want to set the record straight, so that the world is not deceived any longer.
"It is someone else, not me."
The West Kent NHS Trust is trying to identify a man found soaking wet in a black suit on 7 April in the town of Sheerness.
Strnad has ruled himself out
He has never spoken to carers but is a virtuoso pianist.
The National Missing Persons Helpline has said 250 names are being investigated.
The man, who is in his 20s or 30s, stunned his carers with a four-hour concert-standard piano performance after producing detailed pencil drawings of a grand piano.
The man is being held in a secure mental health unit in Dartford, where an upright piano has been installed in his room and doctors are considering using music and art therapy to try to communicate with him.
The search for his true identity has caught the attention of the media not just in the UK, but across Europe.
More than 1,000 people from across the world have contacted the special helpline.
On Tuesday night, the health trust and the missing persons helpline were not immediately available for comment.