Detectives have contacted the family of an elderly woman who lived near multiple murderer John Cooper, and whose body was found in a bath.
Florence Evans was discovered at her home in Rosemarket, Pembrokeshire, 20 years ago.
Although an inquest found no suspicious circumstances, her family never believed it was an accident.
Dyfed Powys Police said there was "connectivity" between Cooper and Mrs Evans.
Cooper, 66, was jailed for life on Thursday for two 1980s double murders which the judge called crimes of evil wickedness.
Cooper, from Letterston, was convicted after an eight-week trial at Swansea Crown Court.
He was also convicted of separate charges of rape, sexual assault and attempted robbery.
Mrs Evans was mentioned by Cooper in his defence evidence. Cooper and his wife, Pat, lived nearby and would visit her at her smallholding.
Known as Flo, Mrs Evans died soon after holidaymakers Peter and Gwenda Dixon were murdered by Cooper on the Pembrokeshire coastal path in 1989.
The body of the widow, who was in her 70s, was found fully clothed in the bath.
Her niece Jean Murphy confirmed that her aunt - who she described as an active, independent woman - was friendly with Cooper and his wife, and that he would visit and do odd jobs for her.
She said Mrs Evans never took baths, and that her aunt would not have had any hot water at the time of her death, as no fire had been lit in the kitchen.
Dyfed-Powys Police say they have a duty to see if Cooper is responsible for other crimes.
Det Ch Supt Steve Wilkins, who led the cold case review into the murders of the Dixons and the 1985 murder of brother and sister Richard and Helen Thomas, said Cooper's trial turned up some "interesting issues" requiring further investigation.
"Clearly, John Cooper himself has introduced Florence Evans into his trial, and we were obviously aware of her prior to us taking the proceedings, and also the circumstances of her death, which were looked at within the coroner's court," said Det Ch Supt Wilkins.
"Clearly, there is connectivity between John Cooper and Flo Evans."
Det Ch Supt Wilkins told BBC Radio Wales' Eye on Wales programme: "There are a number of issues which I think we need to look at; his own history, where he's lived, what he was involved with at the time he lived in different locations.
"At this moment there is nothing concrete that connects him to any other offences, though there are a number of interesting issues which have come out during the trial.
"But also I need to speak to my chief officers as to how we then progress any other investigations, if indeed we do."
"So I will sit down and speak with particularly the family first of Flo Evans, to have those discussions with them, as to whether we should in fact have a look at the circumstances of her death."
BBC Radio Wales Eye on Wales special programme, is available on the BBC iPlayer for a week after its first transmission on Thursday, 26 May.