Her body was found in a ditch in Kilkenny in December that year
Kilkenny gardaí are renewing their appeal for information into the 1984 murder of Marie Tierney.
The 34-year-old was killed on an unknown date between October 21st and December 21st that year.
She was a married woman with two children, aged 12 and 13 at the time.
She lived with her husband and their children at Clintstown, Co Kilkenny where they ran a grocery store and petrol station.
Mrs Tierney was reported missing on October 22nd 1984 by her husband.
She had left their house at Clintstown the night before at around 10.30pm in the family car - a Renault 18 estate, registration number 35-HIP, and had not returned.
Investigating gardaí located the car at Newpark Fenn in Kilkenny on October 22nd.
Statements from a number of witnesses put the car abandoned in Newpark at approximately 11.00pm on the 21st.
A number of searches were carried out by gardaí and members of her family and friends, but Marie could not be located.
Then on December 21st, her body was found by a man out walking on the Bleach Road, Kilkenny in a ditch.
A post mortem examination was carried out and a murder investigation was launched.
Gardaí say over 500 lines of enquiry have been opened, and over 200 witness statements recorded.
"This murder investigation is still very much ongoing and will remain so. There have been no arrests to date for the murder of Marie Tierney", the gardaí say in a statement.
They will be speaking to everyone who made statements in relation to the investigation, and are appealing to any person who may have information into her death to come forward.
Gardaí are again appealing for persons who saw the Tierney family car to come forwarded, and those who had not previously come forwarded.
They are appealing to any member of the public who may have seen people walking or cycling at or near Newpark/Newpark Fenn, Kilkenny on the night of October 21st 1984.
And they are appealing to people who have not yet made themselves known to gardaí or who, for whatever reason, were unable to make themselves available at the time.
"With the passage of time relationships may have changed or circumstances may have changed which may enable persons to come forward with information to gardaí that they may not have done previously.
"Time may have given context to something they felt was unimportant at the time but may be of assistance to the investigation", the gardaí add.