Detectives are offering a reward of up to £15,000 for information regarding the disappearance of two women who vanished from the same stretch of road more than a decade ago.
Student Elizabeth Chau, 19, was last seen by friends on Ealing Broadway in west London shortly after leaving her university campus in April 1999.
Nine months later, office worker Lola Shenkoya, 27, vanished from the same area following a day at work and has not been seen since.
Officers from the Metropolitan Police said they have not ruled out that Miss Chau is alive and well but "fear the worse."
They also described Miss Shenkoya's disappearance as "totally out of character".
DI Andy Manning, who is leading the investigation by the Met's Homicide and Serious Crime Command, said the two disappearances were being linked for investigative purposes only.
He said: "It is 11 years since Lola went missing. Both Lola and Elizabeth went missing from the Ealing area and we would like to enlist the help of the public to see if we can get any nearer to finding out what has happened to these two young women. I am hopeful the offer of a reward will further encourage members of the public to come forward.
"The Metropolitan Police Specialist Crime Directorate is committed to the process of continually reviewing this and other unsolved investigations in order to establish what has happened: this is particularly important for the families of Elizabeth and Lola."
Miss Chau, from Vietnam, left Thames Valley University in Ealing at around 5pm on Friday 16 April 1999. She was seen by a friend in Ealing Broadway at 5.30pm and last sighted walking past Ealing Police Station just after 6pm. She is described as 5ft 2ins tall, slim, with brown shoulder length layered hair.
Police said Miss Shenkoya, who was a devout Christian, went missing from Ealing on Monday 3 January 2000 after spending the day working as a temp at Entertainment UK in Perivale.
She was last spotted getting off a bus outside a Burger King near to Ealing Broadway Underground Station and is described as black, 5ft 5ins tall, slim with brown shoulder length hair.
Police said her bank accounts have not been touched since her disappearance and she has no other way of supporting herself.
Anyone with information should contact the Metropolitan Police on 0202 358 0300 or Crimestoppers anonymously on 0800 555 111.