But watching police officers quickly stopped her to prevent the cleaning

The woman went under a police 'do not cross' cordon to collect the litter

Her thoroughness is to be commended, but this street cleaner is clearly not a big fan of CSI.

Had she been better acquainted with the hit US TV drama, she might have known that a crime scene should be left untouched – at least until police forensic teams have picked it over for clues.

However, the cleaner ignored a police tape cordon, stepped under it and carried on sweeping the road – scene of a fight the night before that left one man in hospital.

The road sweeper ducks under the police cordon to pick up rubbish despite the forensic investigation

Witness James Galbraith said she had been tidying up the bus stop before she wandered through the cordon

‘She was just tidying up by the bus stop when she wandered through the cordon and carried on,’ said railway worker James Galbraith who photographed the cleaner’s brush with the law near Romford railway station in Essex.

‘How she could have missed it I don’t know. All the buses had to be diverted around the crime scene.

‘It takes quite a lot to walk through a big police line with a police officer guarding it that says “Do Not Cross”!’

‘I really couldn’t believe it but she’s a regular at cleaning this part of town.’

Eventually a police officer approached the cleaner to interrupt her efforts and let her know that she was disturbing a crime scene.

Mr Galbraith, 21, added: ‘She was there for two or three minutes before the police officer came over and had a few words. She just left and carried on sweeping up elsewhere.’

Police quickly interrupted to inform her she couldn't clean the crime scene on South Street, Romford

A Metropolitan police spokesman said: ‘Officers did have to explain to a street cleaner that the area in the cordon could not be cleaned.’

Two men aged 20 from Dagenham have been arrested after an incident near Romford station in which a man off 33 was taken to hospital with facial injuries.

The dispute is believed to have started after a group of men were thrown out of a nightclub in the town.

CSI – Crime Scene Investigations – launched in 2000 and has been repeatedly named by the TV industry as one of the most watched dramas in the world.