An investigation has been launched into how a convicted killer was able to volunteer with a city Scouts troop without a crucial background check.

The situation has emerged after an anonymous tip-off to this newspaper that a man who killed his wife in 2004 had helped the 35th Norwich Sea Scouts, based in Mousehold Avenue. 

Gareth Lewis was sentenced to more than three years in prison for plunging a kitchen knife five-and-a-half inches into his 42-year-old wife's abdomen after details of her affair came to light and their marriage quickly deteriorated.  

Gareth Lewis was convicted of the manslaughter of his wife in 2005 Gareth Lewis was convicted of the manslaughter of his wife in 2005 (Image: Newsquest)

Lewis, who was living in Bury St Edmunds at the time, denied it was murder but admitted manslaughter by reason of diminished responsibility, citing depression and medication side effects as having impaired his judgement.

After serving his sentence, Lewis was forbidden from seeing his children, who were present at the time of the stabbing, and he relocated to Norwich where he is believed to still be living. 

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The anonymous source said Lewis was brought on as a volunteer for an outdoor pioneering activity with the Scouts group and that he had "distributed gifts" to the children, raising serious alarm bells. 

Lewis was sentenced to more than three years for the slayingLewis was sentenced to more than three years (Image: Newsquest)

It was then revealed that he had not been DBS (Disclosure and Barring Service) checked before being invited to supervise the troop, aged between 10 and 15 years old, which is a vital requirement. 

The Scouts organisation, which has more than 430,000 members across 7,500 groups nationally, took swift action once it had been made aware. 

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A spokesman said: "We are aware that Mr Lewis supported the Scout group informally on a single occasion.

"He is not a member of Scouting and will never be allowed to volunteer with us in the future.

The Scouts organisation has launched an investigation into how Lewis was able to volunteer without being checkedThe Scouts organisation has launched an investigation into how Lewis was able to volunteer without being checked (Image: Google Maps)

"The circumstances surrounding this are currently being investigated and it will never be allowed to happen again.

"The safety of young people in our care is our number one priority."

The spokesman also confirmed that another volunteer with the 35th group had been suspended pending the outcome of the investigation.