Overview
- Gardaí arrested three men on Tuesday and later detained a teenager, with all held in Midlands stations under Section 50, which allows up to seven days of questioning.
- The blaze began when a petrol bomb was thrown through a front window on December 6, killing four-year-old Tadgh Farrell and his great-aunt Mary Holt and seriously injuring his grandmother.
- Investigators have not announced charges, and the justice minister has said one line of inquiry examines involvement by people in the drugs trade.
- A man arrested in January was released without charge as the months-long investigation continued.
- Detectives earlier searched homes in Kildare and Offaly and released CCTV that appeared to show two hooded figures smashing a window before hurling a flaming object.