It is one of Kent's strangest mysteries. And 15 years on, it is still not known for sure how a young man from Bavaria ended up wet and lost on a beach on the Isle of Sheppey.
It was shortly before midnight when bemused police officers found him dripping wet and peering into McDonald's in Sheerness.
He was wearing a smart, dark suit but with no identification. Even the labels had been removed.
It looked like he had washed ashore at The Leas, Minster. Concerned onlookers spotted him near an abandoned boat and called police.
Officers eventually found him wandering in town and were even more puzzled to discover he could not, or would not, talk.
With little other options, they dried him, as best they could, and took him by patrol car to Medway Maritime Hospital's accident and emergency department at Gillingham.
After doctors gave him a clean bill of health, the mystery man was handed into the care of social worker Michael Camp. And so began a four-month saga as the world's media struggled to solve the secret identity of the stranger who became known as 'Piano Man'.
Left alone with a sketch pad to write down his name, he drew a picture of a grand piano instead.
Puzzled, Mr Camp took his new charge to the hospital's chapel where he was amazed by an instant transformation. As he sat at the keys of a piano, the stranger became calm and relaxed for the first time.
He could even play surprisingly well and was heard reciting sections from Swan Lake by Tchaikovsky and what appeared to be his own compositions.
After three weeks without any sign of recovery, a desperate Mr Camp turned to the Daily Mail to help launch a public appeal for information. Freelance photojournalist Mike Gunnill from nearby Upchurch was despatched to take pictures.
The former Kent Evening Post photographer recalled: "It was a Friday afternoon and I was looking forward to the weekend when I took a call from the picture desk.
"They said it probably wasn't much of a story but a man had been washed up on a beach and had lost his memory. Could I go and check it out?"
So, on May 6, 2005, Mike turned up at the hospital.
The social worker had been given permission to help get a photo but the mystery man would scream whenever he saw a new face. So the pair hatched a plot.
The photographer hid in bushes with his Nikon F3 film camera and 300mm lens and half an hour later Mr Camp led his charge through the hospital's grounds for a walk.
Mike, 69, said: "I only managed to fire off five shots before the man spotted me and became distressed, covered his face with his plastic music folder and started making strange noises."
But those were the only five shots ever taken of the man. Mike said: "Even then, I wasn't sure I had what we needed."
He drove home and spent an agonising hour in his darkroom processing the film to see the results.
Of the five shots, two were no good. The others captured a frail, lightly-bearded figure with spikey blond hair, wearing his by now dried-out suit and white shirt and with every possible button done up.
Mike emailed them to the Mail's picture desk in London and explained that the man wasn't talking but loved playing the piano.
"Like a piano man?" replied a weary voice at the other end of the phone.
Three weeks passed but still the photos had not been used.
Then a concerned Mike received a call saying the executives weren't going to use his pictures because they believed the man was an asylum-seeker and it was an elaborate hoax. But Mike was welcome to sell the pictures to anyone else.
The Mail was not alone. The manager of a pub near where he was found maintained the stranger was "just another illegal immigrant" who had either jumped ship or been pushed overboard by people smugglers as coastguards closed in.
Instead, it was down to the Mail on Sunday to break the news on May 15. Mike's front page photo unleashed a worldwide media storm as news organisations fought to be the first to find out who the mystery man was.
Only later would he be unmasked as 20-year-old German Andreas Grassl.
Mike recalled: "My phone started ringing at 6am the next morning with requests from all the other nationals to use my photographs and the calls didn't stop until midnight.
"The following day there were calls from the foreign media. One magazine in Japan even tried to make me say the man was an alien from outer space!"
Mike was also accused of taking the photos illegally until it was pointed out they had been shot with permission. Sale of the photos netted him an estimated £35,000. They are still used in psychology text books.
'Tortured artistic genius'
Patrick White, a writer and broadcaster who teaches at King’s College London and has spent much time on the Island researching the mystery, recalled: "After the man was sectioned for his own safety and began playing the piano carers encouraged him to play more, presenting him with sheet music of Lennon and McCartney tunes and admiring the ease with which he played them at sight.
"They decided this troubled young man might actually be the real thing: a brilliant but tortured artistic genius who must have suffered some sort of nervous breakdown after a disastrous performance and not even had time to change out of his concert clothes before stepping onto the boat from which he would leap, distraught, as it approached the Thames estuary and end up on Sheppey.
"It was thought he was probably British and that there might be an orchestra or music academy somewhere missing a pianist."
Interpreters were unable to discover his origin and orchestras around Europe were contacted in a bid to trace his identity.
After the appeal for help, more than 800 calls swamped the National Missing Person’s Helpline. Speculation was intense as the story about a person, apparently risen from the sea, was taken up almost instantly all over the world.
Journalists and television crews from far-flung places descended on Sheppey.
"This is really bizarre," muttered a reporter from the Island's local newspaper the Sheerness Times Guardian as he pointed out a Tokyo television crew to a French journalist.
Meanwhile, the man was still playing the piano
Canon Alan Amos, the hospital chaplain, said at the time: "He likes to play what I would call mood music. Playing seems to be the only way he can control his nerves and his tension and relax. When he is playing, he blanks everything else out. He pays attention to nothing but the music."
If allowed to, he would play for three or four hours at a stretch and at times had to be physically removed because he refused to stop.
The 'piano man' was later transferred to Littlebrook Hospital, a secure mental health unit in Bow Arrow Lane, Stone, near Dartford, where manager Ramanah Venkiah said: "He has been playing the piano to a very high quality and staff say it is a real pleasure to hear it. But we don't know what his position is because he is not cooperating at all."
'Are you going to speak to us today?'
During the course of the summer there emerged an endless line of possible names.
There was a performance artist who had been seen in France or Spain, a classically-trained pianist who had once played in a dissident rock tribute band in Prague and a Canadian drifter known as ‘Mr Nobody’ who had tried to enter Britain illegally.
Various women also announced they were certain 'Piano Man' was their missing boyfriend or husband.
By late July, nursing staff were wondering whether their patient’s voice box had been damaged or had been removed. But all speculation came to an abrupt end on the morning of Friday, August 19, when a cleaner went into his room and asked routinely: "Are you going to speak to us today?"
Unexpectedly, the Piano Man opened his mouth and replied: "I think I will. I am not feeling very well."
He explained he was a 20-year-old Bavarian who, far from stepping out of the sea, had arrived in England by Eurostar train from Paris and had been trying to kill himself in the hours before he was picked up by the police.
He told hospital staff he had two sisters and was gay and also admitted he couldn't play the piano particularly well and had only drawn one because "it was the first thing that came to mind."
By the time news of his recovery reached the press, Andreas Grassl was back with his dairy-farming parents in the tiny village of Prosdorf in Bavaria where he would only speak in carefully measured statements issued through the family’s solicitor Dr Christian Baumann.
His father Josef, 46, and wife Christa, 43, were delighted to have their son - one of the most famous missing persons in the world - back home in southern Germany.
Josef, ruddy-faced and wearing green Wellington boots, overalls and cap, wept as he told the Daily Mirror: "We honestly thought he was dead. Not knowing what had happened to him was torture.
"I went to bed every night and woke every morning wondering where he was, wondering if he was dead or alive.
"At one stage I thought it would be better to find out he was dead, just to stop me and my wife going through this torture. She has been terribly upset and bothered with her nerves."
When Andreas was finally reunited with his family at Munich airport he said simply: "Mir gehts gut" - I am fine. Then he said: "I am so happy to be home."
He told Josef: "Dad, you know that I am famous now. I know that my picture has been shown all around the world."
Andreas added: "I just do not know what happened to me.
"I get little flashes of my past, like in a film. But I have no idea how I ended up in England like that, or why I couldn't talk. I just suddenly woke up and realised who I was."
His dad confirmed his son was a talented musician who entertained relatives on an accordion and played a simple keyboard alongside his younger sister.
Josef added: "He knows he had some kind of illness and breakdown but I know he would never make something like this up. He learned to play the keyboard from the age of 10 and can also play the accordion. I think he found some comfort in the piano, except towards the end."
There was still no clue how Andreas reached Sheerness, from his tiny village of Prosdorf near the German-Czech border.
He had no money, no documents and the labels had been cut out of his soaking suit.
Josef said: "He had no passport, no driving licence, nothing. Not even papers or a ticket. He still does not really know how he got into England. He thinks he got a train from France and then maybe a ferry.
"Given that he had no travel documents, I really do wonder, and worry about what might have happened to him.
"Was he attacked or robbed? Hit over the head? We just don't know. He just woke up and suddenly realised who he was. Before that, he could remember nothing, not even his own name."
He added: "Come July, I was going to look for him myself. We honestly thought something had happened to him. He always seemed to be unhappy and found it hard to express his feelings, to show his love.
"But the doctors in England somehow have cured him of that, they have worked a miracle.
"They have given me a new son back. He tells me that he loves me. I cannot put into words how we feel."
'Fraud and sham'
A friend of the family reportedly said Grassl went to a grammar school and had wanted to get into radio or TV or study journalism.
Back in Britain, Grassl was denounced as a ‘fraud’ for not being mute and as a ‘sham’ for not really being able to play the piano.
West Kent NHS and Social Care Trust issued a statement saying he was no longer in the care of the trust, that he had been "discharged following a marked improvement in his condition," and that its "involvement with this man has now ceased and will not be resuming at any stage."
According to an article published in Pink News on May 1, 2007, by which time Grassl was living in Basel, Switzerland, and studying French Literature at university, his last words on the matter were: "That Piano Man stuff, no-one is interested in that any more."
Mr White said: "It still seems possible that, one day, he might look back at that photo and feel just slightly satisfied that he produced an image that kept the snarling contempt for asylum seekers and scroungers at bay for a full season."
The real-life story was turned into a play called The Piano Man in 2014 by London theatre company AllthePigs.
Director Sam Carrack said: “I remember reading the article as a student and getting so excited by it but also the drama and the mystery of these happenings. But the story went cold and we never really got a closure.”
Daniel Hallissey had the tricky job of playing the elusive character and even learned to play the piano for the part.
He said: “For me, the story was a lot about the loneliness we all experience in the modern world and our struggle for identity. Finding out who we are is so difficult in these times.”
Grassl's hospital stay in Britain cost the authorities more than £50,000.
Grassl was born on October 25, 1984, and is now 35.