Three of them are members of the presidential security division, while the other is living in London.
A CID official has refuted reports that suspects in the killing had fled to Italy, adding the three PSD men were in Sri Lanka.
They will be arrested within the next fortnight, he said.
A former diplomat is under investigation over several wrongdoings, including his having aided the suspect in Britain to flee the country.
No vehicle accident
The place from which Thajudeen’s body was recovered does not indicate any vehicle accident having taken place, and his car had more than half of its fuel tank full, the CID said.
His body was found in the front seat next to the driver’s.
The CID will investigate as to whether Narahenpita police had distorted the truth in its report.
The exhumed body will be examined thoroughly, and a judicial medical report is due at courts on September 10.