Inspector General Pujith Jayasundara and former defence secretary Hemasiri Fernando were arrested on Tuesday, a day after Attorney General Dappula de Livera said they should be arrested and charged with "grave crimes against humanity" for failing to prevent the attacks on churches and luxury hotels.
The Attorney General maintained that the the Easter Sunday terror attacks could be considered as grave crimes against humanity.
Releasing his correspondence to the press on Monday evening, de Livera ordered Wickramaratne to immediately explain why Jayasundara and Fernando were not named murder suspects.
For lesser charges of negligence leading to damage of property, the two officials could face up to 52 years in prison.
Soon after de Livera released his communications with the Acting IGP suggesting that he was keen to have the two men arrested, both Jayasundara and Fernando got themselves admitted to hospital.
In June, Mr. Jayasundara and Mr. Fernando testified before a parliamentary panel probing the blasts and pointed to the serious gaps in acting on intelligence.
Some 45 foreign nationals were among the dead and 500 people were injured in the attacks. Nearly immediately after the bombings, Wickremesinghe's cabinet began accusing Sirisena of blocking them out of key intelligence meetings, where officials had reason to know about the impending attacks and could have acted to stop them.
The President blamed them for failing to prevent the Easter Sunday bombings despite receiving prior warnings of a possible attack.
He said he received a letter from a foreign intelligence service warning of an attack on Easter. Since it was not brought up, when the meeting was about to close, I brought it up.
Sri Lanka's State Intelligence Service (SIS) has also been criticised for failing to act on the Indian warnings issues as early as April 4, almost two and a half weeks before the attack, but no-one from the state spy service has been put under investigation.