A person arrested in Dambulla has been identified as the second-in-command of the terror network operated by local Muslim group, the National Thowheed Jamath (NJT), the Daily Mirror reported.
Investigations have also revealed that military training for the assailants was provided by a person called Army Mohideen while weapons training was conducted overseas and at some local locations in the Eastern Province, Nuwara Eliya and Wanathawilluwa.
The assailants had been provided with physical training at a gymnasium, according to the authorities.
The vehicles used in the terror attack had been purchased from a car sales centre in Kadawata.
Sources said that a copper factory operator arrested in connection with the bomb blasts had helped Mohideen by making the improvised explosives devises and helped purchase empty cartridges sold by the military as scrap copper.
Meanwhile, the police on Friday warned that more suspects in the Easter Sunday bombings were on the run.
Authorities in Colombo on Thursday night issued photographs of a number of suspects, but were forced to withdraw one of the images when it transpired that it was of someone who had nothing to do with the bombings.
Adding to the sense of confusion, the government significantly lowered the death toll, from 359 to 253.
The Easter Sunday marked the bloodiest day in Sri Lanka since the end of the civil war a decade ago.