American bodybuilder David Bieber fled the US in 1996 with a fake passport after being implicated in the murder of his wife's lover.
Eight years later, with British residency, he is beginning a life sentence for killing a police constable in Leeds.
Bieber used the identity of Nathan Coleman to evade capture
How did the British authorities let him slip through the net? Is there any way to prevent the same thing happening again?
Bieber married a British woman in March 1997, weeks before his six-month tourist visa was due to expire.
Home Office checks on his background failed to spot that his pseudonym, Nathan Coleman, belonged to a boy who had died decades earlier.
It seems US authorities had not alerted Interpol or the British police that Bieber could have left the country.
"If you are going to have immigration - and immigration cannot be stopped - then there are going to be cracks in the system," says Randall Hansen of Newcastle University.
He argues that the immigration system cannot root out every bad person who comes into the country.
But Professor Hansen says Bieber may have escaped close attention because he comes from the United States.
He said: "He has come from a country from which there is no immigration pressure. If you were to look at every single case like this it would prove very intrusive, expensive and difficult.
"So the Home Office must pay attention to countries where there is a great deal of immigration, like Pakistan, India and Bangladesh."
Foreign nationals hoping to come to Britain legally can enter the country as tourists, students, asylum seekers, workers, or by way of "family formation" or reunion.
David Bieber secured his residency through family formation - by marrying a British woman.
Of the 140,000 immigrants to the UK in 2003, 47% fell into the same category as Bieber.
Those determined to commit crime are obviously very difficult to root out.
The truth of this was borne out in 2000 when Texan pensioner Robert Kleasen was found with a cache of arms in a cottage in Barton-Upon-Humber in Lincolnshire.
Kleasen, it transpired, was wanted in the US for the gruesome double murder of two Mormon missionaries in a taxidermist's shop during the 1970s.
Kleasen was facing extradition proceedings when he died in 2003
He had fled the US in 1990 after serving a jail sentence for other firearms offences. The following year he married and gained UK residency - the same as Bieber.
But Shona McIsaac, the Lincolnshire MP who brought Kleasen to the attention of the Home Office, sees no similarity between the cases.
She says the issue with Kleasen was not identity, but the fact that he was allowed membership to gun clubs.
She said: "After I brought Kleasen to the attention of the then Home Secretary, Jack Straw, the law was changed with regards to allowing foreign nationals membership to gun clubs.
"If he [Bieber] was using a false identity, then that is a very difficult case."
So far, no-one is really sure how a tragedy like Bieber's could have been prevented.
Ms McIsaac did not want to speculate.
Prof Hansen suggests that Home Office checks into his marriage were not thorough enough.
The Home Office was asked to detail the checks they made on Bieber, or on any foreign national marrying in the UK, but they were unable to respond.
Bieber claimed a friend had murdered the police constable
Fabian Hamilton, MP for Leeds North East, the constituency in which Bieber lived, also offered no quick solutions.
"You can't blame the authorities for not having discovered him. He was a ruthless man who was willing to go to any lengths to evade capture," said the Leeds MP.
Mr Hamilton doesn't believe better immigration checks or more up-to-date technology would necessarily have helped either.
Instead, he offered the suggestion of better co-operation between police forces.
"If this man was wanted for murder in the US, and it was clear he had disappeared and perhaps left the country, you would think that the police would notify Interpol - or even the British police.
"After all, the obvious place for an American to come would be the UK."