Paul Bryan was 22 when he stabbed 62-year-old Roman Szalajko at his flat in Kennington, south London, in February 1984.

But within three days, he applied for an emergency passport using the identity of a dead Welshman with the same name as him - and then fled abroad.

Bryan spent the following years travelling around Portugal, Crete, Spain and France and almost escaped justice - until a cold case review in 2013 identified him as a suspect.

In November last year, Bryan applied for a new passport and travelled from Portugal back to the UK - where police were waiting to arrest him at Stansted Airport.

The 62-year-old, originally from Hammersmith, west London, denied murder but was found guilty by a jury at the Old Bailey on Tuesday.

Police believe Bryan had been a "heavy" or "minder" who killed Mr Szalajko while either enforcing a debt or trying to get paperwork after a property deal went wrong.

The court had heard the Polish victim, a divorced father-of-three, was known to be secretive and a gambler who kept large sums of cash at home.

On the morning of 7 February 1984, Mr Szalajko was on the phone to a friend, when he broke off, saying in Polish: "Excuse me a moment, there's someone at the door."

His friend heard the victim say loudly in English: "What do you want? Help, help" before the line was cut.

Police were alerted and rushed to the flat - where they found Mr Szalajko slumped in a living room chair with a stab wound to his stomach.

Officers noticed clumps of his hair had been pulled out and thrown on the floor, while fingerprints were also found at the scene.

The case went unsolved until the cold case review led to the identification of Bryan's fingerprints on a bottle of mead found in a wardrobe at the property.

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Detective Sergeant Quinn Cutler, who then spent 10 years tracking Bryan down, said he appeared to have vanished from all records in the decades after the murder - except for when he was arrested in London in 1997 for a minor drug offence.

DS Cutler said: "There was no record of him having a job since the 1980s, he had not paid any tax, he did not have a passport and he did not have a driving licence. It was like he did not exist".

DNA breakthrough

It was then discovered Bryan had applied for an emergency passport three days after the killing - and that he had been with a woman called Sylvia Bryan when he was arrested in 1997.

Detectives realised the pair married and tracked down their wedding certificate - which revealed Bryan had used a false date of birth. It matched a different man of the same name, and it emerged he had somehow stolen his identity.

"We found out [the original Paul Bryan] was actually dead and this Paul Bryan had then gone on to get a passport and driving licence and was living in Portugal married to Sylvia Bryan," DS Cutler said.

The officer said Bryan tried to pass himself off with his false identity when he was arrested - but "eventually he realised the game was up".

After he was taken into custody, officers were able to take a DNA sample and compare it to material found on Mr Szalajko's vest and clumps of hair found at the murder scene, using technology that was not available at the time.

It proved a "one in a billion" match, DS Cutler said.

'Nothing he says is true'

Bryan tried to dismiss the discovery of his fingerprints as "bulls***" and described the DNA match as "like a bad nightmare".

DS Cutler added: "He also feigned having amnesia and claimed he could not remember what he was doing in 1984, but as the case has gone on we have been able to show he has no memory loss and he's just lying."

Mr Cutler described Bryan as a "fantasist" who lived off his wife's earnings as a tour operator before returning to the UK after her death.

The Lewisham-based officer added: "He has lived the majority of his life as another person. He pretends to be American, he pretends to have been in the army and being AWOL. Nothing he says is true and it's very hard to understand what he has actually done for the last 40 years."

Bryan will be sentenced on 8 December.