The Dhaka Metropolitan Police boss yesterday claimed to have unearthed the conspiracy and blueprint for the murder of Italian aid worker Cesare Tavella.

"We have made remarkable progress. We have uncovered the conspiracy and the plan. You will be informed about it in due time. We are trying to complete the investigation quickly," Asaduzzaman Mia said.

The DMP commissioner was briefing reporters at the DMP media centre on security measures centering on Durga Puja and Ashura. 

He added law enforcers were working to collect evidence against the suspects.

"The mystery of Tavella murder will not only be unveiled, we will present the mastermind behind the killing before the nation," he said.

Tavella, a project manager of Netherlands-based NGO, was gunned down in the high-security diplomatic zone in Gulshan on September 28.

Two men actively took part in the killing, while a third waited on a bike ready to flee, witnesses said. 

No one has been arrested in this connection.

Asked about media reports that mentioned names of three suspects, the DMP boss declined to comment for the sake of investigation.

US-based SITE Intelligence Group, which monitors militant activities, uploaded a post where IS purportedly claimed responsibility for Tavella's murder, but Asaduzzaman reiterated that investigators did not find even the "slightest link" of militant outfits in it.

Asked if police were harassing any "particular quarter," he said there was no question of harassing anyone and insisted that they would do everything on the basis of evidence.

Replying to another query, the commissioner said, "The travel alert issued by the US for its citizen is part of their routine work … They do it regularly in several countries. It is nothing new."

He added police were working on the reported security threats and trying their best to ensure security for all.