The government, which has come under fire for missing multiple warnings that an attack was imminent, believes the ringleader was Zahran Hashim, a fiery 34-year-old preacher from eastern Sri Lanka.
However, half a dozen locals in his hometown of Kattankudy and others who knew him have told Reuters that video surveillance footage taken in a lift before the April 21 attack, showing a man who investigators believe is the bomber, appears to depict a far slimmer man than Hashim, with a different gait.
The clip is short, though, and the man's face is partially hidden by a cap. Hashim had disappeared from public view several months before the attacks.
Colombo Chief Magistrate Ranga Dissanayake ordered state judiciary medical officials to check the bomber's remains against his daughter's DNA.
Dissanayake said he was responding to a request by the criminal investigation department.
A top intelligence official told Reuters that facial identification had confirmed that the dead suicide bomber was Zahran.
"But since there is a dispute, we are going for a DNA test," he said.
Sri Lankan authorities believe the bombings were carried out by two little-known domestic Islamist groups, the National Tawheed Jamaath (NTJ) and Jamathei Millathu Ibrahim (JMI). Islamic State has claimed responsibility.Investigators from eight countries, including the U.S. Federal Bureau of Investigation and Interpol, are helping with the investigation.