Susan Rushworth, 43, was one of three prostitutes killed by student Griffiths at his flat in Bradford.
The dismembered body of Suzanne Blamires, 36, was found in the River Aire, in Shipley, West Yorkshire, last year along with a small part of Shelley Armitage, 31.
But no trace has ever been found of Miss Rushworth, who went missing in June 2009.
At an inquest into her death, Detective Chief Inspector Mark Ridley, from West Yorkshire Police, told the family: “I think it is extremely unlikely, given the passage of time, that Susan’s body will ever be found.”
Bradford Coroner Roger Whittaker told family members in court - including her mother Christine Thompson and her daughter Kirsty Rushworth - that he was sorry they had to hear this detail.
But Mr Whittaker said it was necessary to enable him to conclude the inquest and record a verdict of unlawful killing. He said he was satisfied Miss Rushworth had died of head injuries.
Leeds Crown Court heard last year heard how Griffiths had admitted killing her, hitting her with a hammer. Blood splatters linked to her through DNA were found in his flat and on his boots.
Griffiths, now 41, was sentenced to three life terms after he admitted the three murders last year. He was caught on CCTV killing Miss Blamires with a crossbow at his flat complex on Thornton Road, Bradford.
In a statement released through police after the 15- minute long inquest, Miss Rushworth’s family said: “Susan was a much loved daughter, sister, mother, grandma and auntie.”