Almost 45 years after the Bayswater murder of a widow who had survived the Holocaust, detectives have launched a fresh appeal for witnesses and information with the support of her family.
A reward of up to £20,000 is also available for information leading to the arrest and prosecution of the killers of 68-year-old Emmy Werner in 1972.
Emmy's body was found in her bed by a chambermaid at Queens Hotel, Inverness Terrace, W2 around 13:00hrs on Sunday, 17 September. She had been strangled and suffered several other serious injuries, suggesting she had awoken and disturbed her attacker.
A 16-year-old boy was arrested within a few weeks of the murder and charged. He was acquitted in February 1973 at the Old Bailey.
Officers from the Met's Special Casework Investigation Team are now taking a fresh look at Emmy's murder in the hope the passage of time may provide some clues and encourage people to come forward.
Before the war Emmy, her husband Albert, a dentist, and their daughter Hedy lived a comfortable life in Brno, Czechoslovakia.
But in April 1942 the family and other relatives were forcibly transported to Theresienstadt concentration camp near Prague. In October 1944 Albert was taken to Auschwitz and then, as the Allied troops advanced, onto Kaufering concentration camp where he was killed in February 1945.
Emmy and her daughter, then aged 17, were liberated in May 1945 and came to London in September 1946. They lived with relatives before settling in the Finchley area. Emmy suffered mental ill-health for many years due to her war-time experiences but eventually made progress through treatment. She lived with her mother until her mother's death in 1966.
Emmy then moved to a residential care home in Finchley but visited her sister in central London regularly, staying at Queens Hotel.
On the evening of Saturday, 16 September she had been to Vaudeville Theatre on the Strand with two friends to see Move Over Mrs Markham.
She came back to her hotel around 20:30hrs and settled in for the night.
Detectives believe she was attacked in her room in the early hours of the following morning and the most likely motive was theft. Emmy was known to carry around cash, which she kept in her handbag. It's thought someone came into her room to steal the money and Emmy awoke and disturbed him or her, leading to the attack.
Officers are hopeful people working at or visiting the hotel in the early '70s may have useful information. At the time there were mostly young people of different nationalities both working and staying there, including some German tourists and Swedish staff.
Detective Inspector Susan Stansfield, of the Met's Special Casework Investigation Team at the Homicide and Major Command, said: "Although many years have now passed since Emmy's death it remains particularly difficult for her family that she survived the horrors of the Holocaust yet died in such brutal circumstances. Emmy was 68 years old and was physically and mentally vulnerable due to her past.
"The hotel served a mixture of guests and employed a number of staff who were spoken to by police at the time. However, with the passage of time, it is possible that the events of that night have since been discussed and there is information that could be really useful to our inquiry. Or maybe someone who was scared to speak to officers at the time might now feel able to come forward.
"Did you stay or work at the hotel or in the area of Inverness Terrace W2 in the early 1970s? Has anyone told you anything in confidence that you feel you should now disclose to police?
"We would also be interested in speaking to the friends - one from the hotel and an Italian woman - who Emmy went to the theatre with that night in case they have any useful information.
"We would ask anyone who can help to please contact us in confidence. Even if you think what you know is insignificant, we would ask that you come forward and let us assess what you tell us."
Emmy's granddaughter Carolyn Franks, 58, said: "My grandmother was a vulnerable woman and no one should have to die like she did, especially after the trauma she had already endured. The effect on her close family continues to be a source of great sadness to us and we feel whoever killed her should be held to account."
Anyone with information is asked to contact police on 020 7230 4294 or Crimestoppers anonymously on 0800 555 111.