Two people have been arrested in connection with the discovery of the body an infant in Co Kerry in 1984.
Gardaí arrested a man aged in his 60s and a woman in her 50s on suspicion of murder on Thursday evening in the Munster region.
They are being held at Garda stations in the south of the country under Section 4 of the Criminal Justice Act.
The baby was found with multiple injuries on White Strand Beach in Cahersiveen on April 14th 1984.
In January 2018, An Garda Síochána announced a review into the death of 'Baby John', which would become known as the Kerry Babies case.
An extensive investigation has been ongoing since then, with hundreds of people having been interviewed and over 560 lines of enquiry being followed.
Superintendent Flor Murphy, who has been leading the investigation, is again appealing to the public for any information in relation to the death of Baby John to come forward.
"The arrests are a significant development in this investigation in an effort to establish the truth surrounding the death of Baby John in 1984 and deliver justice for Baby John," she said.
"I am again appealing to the public for any information in relation to the death of Baby John in 1984.
"Anyone who comes forward will be treated with sensitivity and compassion," she added.
Anyone with information is asked to contact Killarney Garda station on (064)-667-1160 the Garda Confidential Line at 1800-666-111 or any Garda station.
Main image shows White Strand beach in Cahirsiveen, Co Kerry. Image: John Cairns / Alamy