Sinn Féin TD Aengus O'Snodaigh has issued a public appeal for information on the whereabouts of his teenage son.
16-year-old Lorcán O'Snodaigh went missing on the same day his older brother Ferghal was stabbed at their home in Bluebell.
When last seen, Lorcán was wearing a blue top and carrying a blue bag.
His father, Sinn Fein TD Aengus O'Snodaigh, 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 Lorcán let me know. He is probably still around Dublin".
Meanwhile, Deputy O'Snodaigh's older son Fearghal is still being treated in hospital after being stabbed in the early hours of Sunday.
The Dublin South Central TD says he's recovering well.
Anyone with information on the stabbing or the whereabouts of 16-year-old Lorcán is asked to contact Gardai.