Sewer death woman 'crawled eight miles through maze of tunnels and then collapsed from poison gas'

The near naked body of Kaylene Lyle, 43, was found in a giant vat at Abbey Wood, south east London.

However, detectives have established that she crawled into a culvert eight miles away in Wandsworth and now believe she may have walked or crawled through the network of large tunnels for around 24 hours before collapsing.

Strange twist: Police initially thought Kaylene Lyle had been strangled. Now they believe she walked eight miles through sewer tunnels before collapsing from poison gas. She was last seen alive at St George's Hospital in south London

One possibility is that she was overcome by sewer gas and fell into the water and drowned.

Experts say the gas causes red marks on the body, which prompted initial fears that she could have been strangled.

Jamaican Mrs Lyle was last seen in an agitated state at St George's Hospital, Tooting, two days before her body was found last Friday in a 10ft-deep settlement tank at Britain's largest sewage processing plant.

Detective Chief Inspector David Garwood said: 'She was in an agitated state and staff sought to secure her for her own safety but she ran away before they could do so.

'From there, we know she sought refuge in a nearby house, but left it via the back garden.

'It is possible that she walked from there along the railway line and entered a culvert belonging to the water company, under the railway bridge in Waterfall Terrace, SW17.'

At first detectives did not fear foul play and believed she had committed suicide.

She had suffered extensive injuries after being caught up in rotating machinary used as part of the treatment process.

A post-mortem showed she had drowned with her lungs full of water. Marks on her neck also suggested that she might have been strangled before ending up in the tank.

Police then discovered marks that appear to show rings were torn from her fingers.

A Scotland Yard murder squad is investigating her death.

A senior source at the Met said: 'The circumstances of her death look extremely suspicious.'

An inquest into her death opened at Croydon Coroner's Court.