Detectives searching for missing teenager Alice Gross have formally requested full details of the murder conviction against the prime suspect in her disappearance, Scotland Yard confirmed.
Police said an international letter of request has been sent to Latvia to obtain the full file on the case of Arnis Zalkalns, who served seven years in prison after he was convicted of bludgeoning and stabbing his wife Rudite Zalkalns to death in his native country.
The operation to find Alice, 14, has come under scrutiny after reports police did not immediately seek help from Latvian authorities in the hunt for the prime suspect.
Officers searching for Zalkalns waited for four days before approaching officials in the country, according to The Times.
The Metropolitan Police were said to have made contact with their counterparts in Latvia over the weekend as the force carries out its biggest search operation since the 7/7 bombings, after Alice, 14, disappeared on August 28.
A Scotland Yard spokesman said: “We are maintaining a close and productive relationship with the Latvian authorities in relation to this investigation. We are not going to elaborate on the nature of information sharing with Latvian authorities.”
The inquiry has focused on Zalkalns, 41, after he too went missing on September 3.
His passport was left at his house in Ealing, west London. Police in Latvia confirmed he has not entered the country by plane but conceded it was possible he could have got in undetected if he travelled by car or coach.
The Metropolitan Police said that 600 officers from eight forces have searched nine square miles of open land and 3.4 miles of canals and rivers in the largest deployment of search assets for an ongoing investigation since the terrorist attacks of 2005.
Alice has not been since she was spotted on CCTV footage walking alongside the Grand Union Canal in west London.
Zalkalns, who was convicted of murder in 1998, was seen 15 minutes later riding past the same spot on a mountain bike.
He has not accessed his bank account or used his mobile phone since he went missing.
Scotland Yard have insisted they have no evidence to suggest that Alice, who suffers from anorexia, has come to harm.
Detectives have said that Zalkalns was also arrested on suspicion of indecently assaulting a 14-year-old girl in 2009, but no further action was taken.
The general labourer, who works at a building site in Isleworth, west London, is thought to have come to the UK in 2007.
Police said on Thursday that it was their understanding there was no record in the UK of his murder conviction.
A reward of up to £20,000 is being offered for anyone who has information that leads detectives to find Alice.
Zalkalns is described as white, 5ft 10ins, of stocky build and with dark brown hair that he normally wears tied in a pony tail.
Police have said that he “potentially poses a risk to the public” and asked anyone who sees him not to approach him and to dial 999.