A reward of up to £20,000 is available for witnesses or those with information leading to a conviction of the murderer of a Holocaust survivor in 1972, as detectives launch a new appeal.

Emmy Werner, 68, was found strangled in her bed by a chambermaid at the Queens Hotel in Inverness Terrace, London, at around 1pm on September 17, 1972.

Mrs Werner, who was living in a residential care home in Finchley at the time of her death, suffered other serious injuries, which suggested she had awoken and disturbed her attacker.

Times Series: Emmy, aged 58, with her grandchildren

Before the war Emmy, her husband Albert, a dentist, and their daughter Hedy lived in Brno, Czechoslovakia, before being transported to Theresienstadt concentration camp near Prague in April 1942.

Mr Werner was taken to Auschwitz and then onto Kaufering concentration camp where he was killed in February 1945, but Emmy and her daughter, then aged 17, were liberated in May 1945 and came to London in September 1946, where they lived with relatives before settling in Finchley.

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."

Times Series: Queens Hotel in Inverness Street, London

On the evening of her September 16, Emmy had seen Move Over Mrs Markham with friends at the Vaudeville Theatre in Strand, and returned to her hotel at around 8.30pm to settle in for the night.

Police believe the motive may have been theft as she was known to carry around cash in her handbag.

Officers are hopeful people working at or visiting the hotel in the early 1970s may have useful information, as many young people of different nationalities were both working and staying there, including some German tourists and Swedish staff.

Anyone with information is asked to contact police on 020 7230 4294 or Crimestoppers anonymously on 0800 555 111.