"In our investigation, we have so far found that these seven people are not directly involved in Babu killing. But they motivated the killers to do it," DB Joint Commissioner Monirul Islam told the Dhaka Tribune yesterday.
He also claimed that the two killers, caught just after killing Babu on March 30, did not belong to Ansarullah but were followers of its chief Jasim Uddin Rahmani who professed to kill atheists.
"We also suspect that some of these seven killers were present when Babu had been attacked [at Begunbari of Tejgaon]," said Monirul, also the chief of DB police, who are investigating both the cases.
On February 27, US citizen Avijit was murdered near the TSC intersection of Dhaka University after he came out of the Amar Ekushey Book Fair. His wife, Rafida Ahmed Bonya, lost a finger in the attack.
Babu, who was vocal to demand justice for Avijit murder, was killed while going to office. The two detained killers in interrogation earlier said they had seen Avijit's killers at a mess in Jatrabari area.
Monirul hopes that they will be able to solve mystery behind the killings after the arrest of the seven suspects. "Two of them launched the attack on the couple with machetes while the five others took position around the spot," he said.
"We have verified their identity and photos by analysing the evidence with technological help."
One of them is a medical student while the others are also highly educated. "Their age is below 30. They learnt about Avijit through Facebook."
The DB chief says all the members of the team were highly expert in making bombs, operating arms and other technical issues.
"We suspect that they belong to a single sleeper cell of Ansarullah and this is why a Twitter account named Ansar Bangla 7 took responsibility of the murder."
The DB official said the turbans had tried to kill Avijit several times after the couple came to Dhaka on February 16.
He said they had all necessary evidence to prove the case against the seven holy warriors. "We are now trying to trace their location. Their names can be fake too, but we have their photos." Asked about the involvement of Buet teacher Farseem Mannan Mohammedy, Monirul replied in the negative.
Earlier, Rapid Action Battalion
members incarceratedMaw! They're comin' to get me, Maw!
Shafiur Rahman Farabi, a leader of banned holy warrior outfit Hizbut Tahrir
...an al-Qaeda recruiting organization banned in most countries. It calls for the reestablishment of the Caliphate...
, for instigating the murder of Avijit. He had been threatening to kill the writer, professionally a biomedical engineer, since 2012.
Asked about getting any feedback from the US Federal Bureau of Investigation (FBI), Monirul said: "We are yet to get the lab results of the evidence collected from the murder spot. But they have expressed contentment with our findings."
He said the DB contacts with Bonya through the FBI officials in the US.