The Crown Prosecution Service’s special crime division is considering whether to charge MP Mike Amesbury after CCTV showed the politician punching a man in the street.
While the police are responsible for collecting evidence, the Crown Prosecution Service (CPS) is responsible for whether someone should be charged with a crime.
Cheshire Police has now handed the file to the CPS.
Mr Amesbury, MP for Runcorn and Helsby, voluntarily met with police following the incident in Frodsham, but has not been arrested.
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Because of his position as a member of parliament, the case has been passed to the special crime division of the CPS in London, rather than the local department in the North West of England.
CCTV footage showed Mr Amesbury facing off for about 30 seconds with another man, before the MP hits the other person in the face.
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It is not clear what the pair were talking about – although Mr Amesbury claimed he was “threatened on the street following an evening out with friends”.
Elected as a Labour MP, Mr Amesbury has been suspended from the parliamentary party while an investigation takes place.
Cheshire Police said a 55-year-old man was voluntarily interviewed under caution and “released pending further enquiries”.
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The MP said in a statement he had contacted “Cheshire Police myself to report what happened during this incident”.
The incident happened in the early hours of Saturday in Main Street, Frodsham, near Cheshire.
In July last year, a 56-year-old man was convicted of stalking Mr Amesbury at his constituency office.
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Video of Mike Amesbury incident
Prosecutors said he was seen staring through the glass and asked guards about their level of security.
The CPS confirmed it had received a file from Cheshire Police.
Cheshire Police, and the Labour Party have been approached for comment.