The body of 53 year old Martin Mulligan was found near his car in Kilcurry, Dundalk on the 28th of September.
He had suffered a number of stab wounds.
Gardai are appealing for anyone who was in Mr Mulligan's taxi during the night or any motorists who were on the Dublin to Armagh Road between 1am and 3.30am on Monday morning to contact them.
