People always seem to get hooked on a missing person case, whether it be through watching documentaries, doing some digging online, or keeping up with investigations.
But what about the case of someone who 'never existed' at all?
This is exactly what happened in Sligo, Ireland, in what is now widely known as the Peter Bergmann case.
A man's body was found on a Sligo beach days after he checked into the Sligo City Hotel on 12 June 2009, where he stayed most of the time throughout his visit to town.
While much of his movements and whereabouts were caught on CCTV, the reason for his visit still remains unknown by authorities.
The man had no documents and left no trace (YouTube/@AeonVideo) The man checked in with the fake name 'Peter Bergmann', paid with cash and carried a worn-out bag, while providing an Austrian address as his home: 'Ainstettersn 15, 4472, Vienna, Austria'.
Standing at a slender 5ft 10in build with short grey hair, blue eyes and a slight tan, it was believed that he was in his late 50s or early 60s.
Staff at the hotel noted that he spoke with a thick German accent.
He had made his way from Ulster, with no record of entry into Ireland, and it was assumed from his appearance that he was a professional worker and was seen smoking frequently in surveillance footage.
For the following three days, he could be seen leaving the hotel with a purple plastic bag full of items, and every time he returned, it was empty.
He stayed in Sligo for a few days (Getty Stock Image) Authorities never worked out he threw away, as he discarded it in blind spots of the CCTV cameras. It was noted that his movements appeared calculated, and almost planned.
Bergmann was also seen buying eight international stamps from the post office with air mail stickers, and the next day, he asked a taxi driver for a nice quiet beach location where he could swim.
He suggested Rosses Point, before driving him there. The same driver returned and dropped him off at the bus station in the town.
On 15 June, Bergmann checked out of the hotel at around 1pm, still without an ID or passport.
The unidentified man known as 'Bergmann' was found dead on Rosses Point Beach (YouTube/@AeonVideo) The peculiar case didn't end there though as he headed back to the bus station with a black shoulder bag, a purple plastic bag, and a different black luggage bag, with no trace of the bag he had when he arrived.
At a cafe, he could be seen with a coffee and a sandwich, writing something on a piece of paper before staring at it for a few minutes and then tearing it up and throwing it away.
In the afternoon, Bergmann headed back to Rosses Point Beach, where reports said he was seen by 16 people as he stood on the beach, fully dressed, with his shoes in hand.
He was spotted at 10:50pm, still pacing, and even had a brief encounter with a local on the beach, who said hello to him.
But on the morning of 16 June, his body was discovered at the beach by a father and son, with his clothes found on the shore nearby, as he was only wearing a t-shirt and underwear.
Following a five-month investigation, the Gardaí could not identify him or find any leads.
A post-mortem took place and revealed that he was in poor health.
In fact, it revealed that he had advanced stages of prostate cancer and bone tumours, while his heart had signs of previous ischaemic heart disease - despite all of these conditions, there was no trace of medication in his system.
The official cause of death was determined to be acute cardiac arrest, as there was no water in his lungs, with no signs of struggle or injury.
It is thought that his heart failed just moments before he went into the sea.
16 years on from the incident, the man is still unidentified, with no relatives or friends coming forward. Authorities also made public appeals in Austrian and German publications in an attempt to find out who he really was.