The family of a primary school teacher stabbed to death in her flat 20 years ago have made a fresh appeal to trace her killer.
Joy Hewer was sexually assaulted and left for dead in her Walthamstow flat on October 17 1995.
The 52-year-old's injured body was found in her bedroom with multiple stab wounds after two fires were deliberately started.
Ms Hewer's younger sister Penny Barnes appealed for anyone with information to come forward.
"We need to see closure and can't face another 20 years of unanswered questions."
Police are now trying to trace a man captured on CCTV going into Joy's flat the night she died.
Forensic teams found no sign of forced entry which suggests Ms Hewer may have known her killer.
There were also two used coffee cups in her flat in St David's Court.
A white man, aged between 30 and 40, who would now be between 50 and 60, was caught on CCTV entering the flat around 10.30pm that night.
Although the images appear grainy, officers believe those close to the man would still be able to recognise him.
Ms Barnes said her sister was "absolutely no harm to anyone" and "would go out of her way to help others".
She added: "We've never forgotten the moment we were told she'd been murdered. It will never make any sense to us.
"She'd enjoyed her work as a teacher, adored her nieces and nephews and was fantastic with children.
"She regularly attended church and often helped at charity events. She lived a quiet and peaceful life which was totally at odds with her last terrifying moments."
Police are also searching for other people who may have crucial information.
This includes the man who called the fire service on the night of her death from a public phone on Fulbourne Road and a person waiting at the bus stop who he spoke to during the call.
Detective Inspector Susan Stansfield, who is leading the investigation, said: "After two decades we realise a lot of time has passed and someone who may have not spoken out in 1995 may feel they can come forward now, 20 years on.
"Joy's parents have sadly passed away but her brother, sister and nieces and nephews still very much hope to see someone brought to justice.
"We hope that this latest appeal will enable someone with the final piece to the jigsaw to speak out."
Anyone with information should contact the incident room on 020 7230 7963 or Crimestoppers anonymously on 0800 555 111.