Media playback is unsupported on your device Media caption Arnis Zalkalns was last seen on 3 September - a week after Alice Gross disappeared

A man wanted in connection with the disappearance of 14-year-old Alice Gross was convicted of murdering his wife in Latvia, police have revealed.

The schoolgirl was last seen on 28 August when she was spotted on CCTV by the Grand Union Canal in west London.

Latvian builder Arnis Zalkalns, who used the same route to get to work, went missing a week later.

The 41-year-old served seven years in prison for murder in Latvia after being convicted in 1998, police said.

He was also arrested in the Ealing area of west London in 2009 on suspicion of indecently assaulting a 14-year-old girl, but no further action was taken.

Det Supt Carl Mehta, from Scotland Yard's Homicide and Major Crime Command, said Mr Zalkalns may pose a risk to the public.

He added that he was not wanted in Latvia, he had served his time and had not been on police records in the UK.

Media playback is unsupported on your device Media caption Officers searching the property removed a large item covered in brown paper from the garden, as Sophie Hutchinson reports

Toms Sadovskis, a spokesman for Latvian state police, confirmed the suspect was convicted in 1998 for the murder of his wife, but the spokesman was unable to discuss details of the crime, or the nature of the assistance being provided to British police.

Scotland Yard said it would need to obtain an International Letter of Request to get full access to the file on Mr Zalkalns.

Forensic searches were being carried out at Mr Zalkalns' family home on Thursday.

Mr Mehta stressed that police had no evidence suggesting Alice had come to harm.

"This is not a murder inquiry in the sense that we don't have any evidence or information to say that Alice is not alive," he said.

Mr Zalkalns was seen on CCTV on 28 August cycling along Brentford Lock at 16:00 BST, 15 minutes after Alice has walked the same way. He was last seen on 3 September.

Mr Mehta said: "He was travelling in the same direction as Alice, about 15 minutes behind on a pedal cycle. He certainly came past her or into contact with her.

Image copyright Family handout Image caption Alice Gross was last seen near the Grand Union Canal on 28 August

"What happened at that point is a focus of our investigation."

Asked if he posed a threat to the public, Mr Mehta said: "I think given what we are finding out about his antecedents and his history, clearly he potentially poses a risk to the public.

"I would ask if anyone sees him not to approach him but to immediately dial 999 and contact the police."

Mr Zalkalns became a person of interest on 12 September, Mr Mehta said, but he had come to the notice of police before that.

Officers have said Alice's missing smartphone may hold "key" information about her disappearance. The device last connected to the network at just after 17:00 BST on 28 August.

A couple saw her bag on 28 August at about 22:15 BST on the footpath that runs besides the River Brent between Hanwell Bridge and the Grand Union Canal.

Police also appealed for the public's help tracking down Mr Zalkalns' red Trek mountain bike.

Media playback is unsupported on your device Media caption CCTV images show Arnis Zalkalns on a bicycle in west London

They have received more than 100 calls to their #FindAlice investigation after an appeal on BBC Crimewatch earlier this week.

A reward of up to £20,000 is being offered for anyone who has information that leads police to find the missing girl.

Alice's mother Rosalind Hodgkiss told Crimewatch: "There's not a moment of the day that you don't think about Alice and where she is, what might have happened or why she might have gone missing.

"It's almost impossible to describe what that pain feels like but we just want her to know: please Alice, if you're out there, come home."

Image copyright Met Police

Scotland Yard has released an interactive map of the route Alice took.

Mr Zalkalns has been in UK since 2007 and had been working as a labourer on a building site in Isleworth, west London before he disappeared.

He has a partner and young child living in Ealing and is described as 5ft 10in, stocky with dark brown hair he normally wears in a pony tail.

Since he was last seen at his home on the evening of Wednesday 3 September he has not accessed his bank account or used his mobile phone and his passport was left at his house.

Mr Mehta said: "The family and friends of Arnis Zalkalns have no explanation for his disappearance, it's inexplicable as far as they are concerned."