He is accused over granting a tender to a company owned by the father of a woman constable working under him, Rasika Priyanthi (WPC 4394).
The auditor general found the irregularity and informed the speaker, who has instructed the IGP to investigate Weerasuriya.
An investigation under Ajith Rohana by the Special Investigation Unit found both the DIG and the WPC guilty.
The former escaped with a warning letter while the latter was served with a charge-sheet.
However, only the NPC has powered to issue such a letter.