A man in his 40s has been arrested in connection with the murder of Irene White in Dundalk in 2005.
Ms White, 43, was killed at her home in the Co Louth on 6 April 2005.
This evening a man was arrested and is being held at Dundalk Garda Station.
Anthony Lambe admitted killing Ms White, saying he did so on behalf of another individual.
Ms White had three children, aged 17, six and four, and had just done the school run when she was killed.
Her 79-year-old mother called to see her just before lunchtime on 6 April 2005 and found her lying in a pool of blood. She had been stabbed 34 times.
The case was reviewed by the garda cold case review team.
An appeal for information about her death was made by gardaí in 2016.