[1] Nugagaha Kapalle Illangakoon was born on 12 April 1956 in Balangoda,[2] the youngest in a family of five.
[2] He taught Mathematics and Social Science at Hambegamuwe Maha Vidyalaya in Thanamalwila.
He served in Jaffna, Ampara and Batticaloa as Area Commander.
[2] Illangakoon was appointed as the Director Special Branch in 1999 and promoted to Deputy Inspector General of Police.
[4] Following the deadly Easter bomb attacks, Illangakoon was appointed as an advisor to the Ministry of Defence in April 2019,[5] and appointed a member of the Presidential Commission of Inquiry on the Easter Attacks headed by Justice Vijith Malalgoda, and including former Law and Order Ministry Secretary, Padmasiri Jayamanne, tasked with investigating the causes and background for the 2019 Sri Lanka Easter bombings.