The dying plea from the mother of Lady in the Lake victim Carol Park was to never let her daughter's 1976 disappearance go unsolved.
Carol Park was bludgeoned to death with an ice axe by her husband
Carol Park's brother, Ivor Price, told the BBC that his mother's dying request was to "keep looking for Carol".
On Friday, Gordon Park, 61, from Barrow in Cumbria was jailed for his wife's murder, 29 years after she disappeared.
Her mother made the plea in the 1980s, before her daughter's body was discovered at the bottom of a lake.
The mother-of-three, then 30, disappeared in 1976, and her remains were found 21 years later in Coniston Water by amateur divers.
Park had bludgeoned her with an ice-axe, before wrapping her body in bin liners and dumping it in the lake, weighted down with stones.
Mr Price said: "The last time I spoke to our mother, she told me to never to stop looking for my sister.
"I felt for my mother right through this. In a sense I'm glad she was spared the agony of the last seven years, but I wanted justice for her too.
"In 1976, I had to accept what Gordon was telling me - that Carol had left him. I had no reason to think otherwise.
"But less than one minute after the news that a body had been found in the lake, I said to my wife 'this is Carol.'
"I knew it was her, and I knew who had done it."
Park was jailed for life at Manchester Crown Court and told he must serve at least 15 years.