Shahidul Ahmed, 41, was put on trial after DNA evidence linking him to Rachel Manning's death was discovered following his arrest for an unrelated matter in 2010.
He hit Miss Manning repeatedly with a steering lock after she was dead, causing broken bones, Luton Crown Court heard.
DNA found on the steering lock matched Bangladesh-born Ahmed after it was discovered by the road on the direct route between the spot where the body was hidden and Shahidul Ahmed's home.
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Ex-pro Billy Seymour said Higgins broke down and got on his knees to try to stop him leaving the squad.
Mr Charles died in hospital after he was chased by a police officer into a shop in Dalston and restrained.
The 23-storey site was developed at the old Windsor House office block.