Saturday will mark four decades since Brenda Page was discovered in Allan Street, Aberdeen, but no-one has been brought to justice over her killing.
Following instruction in 2015 to re-investigate the case, Police Scotland and the Crown Office have continued to carry out enquiries.
Her sister Rita Ling said: “Forty years have passed since Brenda was found and not a day goes by when we don’t think about her and the horrendous ordeal she must have suffered that night.
“Brenda was an extremely intelligent woman with her whole life ahead of her.
“It pains us to think of the great things she would have undoubtedly achieved.
“It is important the police and Crown Office have all potential information available to them to bring the person responsible for her death to court.
“Please come forward if you think you can help.”
Ms Page worked in the genetics department at the University of Aberdeen Medical School from 1973 until the 32-year-old’s murder in 1978.
Officers have spoken to many of her former colleagues but are now urging any others not previously in contact to get in touch.
Police Scotland said it is trying to build up a picture of what happened in the run-up to Ms Page’s death.
Detective Inspector Gary Winter, of the major investigation team, said: “I must stress that our enquiries don’t just focus on Friday July 14, 1978 and the hours leading up to her body being found.
“It is crucial we build a picture of Brenda’s life generally as part of our enquiries, which is where her neighbours, friends and colleagues come in.
“I appreciate this was a long time ago, however if you do remember anything, I urge you to come forward.
“Forensic techniques and processes have changed dramatically over the past 40 years and we continue to use every resource at our disposal to explore information relating to this case. It is crucial someone is brought to justice for Brenda’s murder.”
Those who may have information have been urged to contact officers by calling 101.