UPDATE: Lorcan Ó Snodaigh has been found safe and well.
Sinn Féin TD Aengus Ó Snodaigh has issued a public appeal for information on the whereabouts of his teenage son.
16-year-old Lorcan Ó Snodaigh went missing on the same day his older brother Ferghal was stabbed at their home in Bluebell.
When last seen, Lorcan was wearing a blue top and carrying a blue bag.
His father, Aengus, posted a picture of him on his Facebook page and is now appealing for the public's help in tracking him down.
He also posted a message which reads: "If anyone sees Lorcan let me know. He is probably still around Dublin".
Meanwhile, Deputy Ó Snodaigh's older son Ferghal is still being treated in hospital after being stabbed in the early hours of Sunday.
The Dublin South Central TD added he is recovering well.
Anyone with information on the stabbing or the whereabouts of Lorcan is asked to contact Kilmainham Garda station on 01-6669700, the Garda Confidential Line on 1800-666-111 or any Garda station.