A man has been arrested in India over the murder of a woman who was found dead in a children's play area, police said.
The body of 35-year-old Michelle Samaraweera was discovered in the small park in east London in May 2009. She had been raped and strangled.
Indian authorities have now picked up a 26-year-old at New Delhi airport in connection with her killing and another three sexual assaults.
A spokesman for the Metropolitan Police said the force would be seeking his extradition to the UK.
Ms Samaraweera was murdered as she returned to her boyfriend's home in Walthamstow after stopping at a local supermarket.
She was found in a park off Queens Road in the early hours of May 30 2009.
Police launched a massive investigation into the killing and the three DNA-linked sexual assaults.
The first, on a 59-year-old woman, took place in her own bedroom at 1am on March 24 of that year.
It came after she returned to her home near Queens Road and noticed a man standing close by as she approached the front door. He forced his way inside and raped her.
The second assault, on a 46-year-old woman, happened after she was pushed into an alleyway in the same part of the capital in the early hours of April 22. The third, on a 32-year-old woman, took place at a similar time on April 29 in the grounds of nearby St Saviour's Church, on Markhouse Road.