Criminal charges were filed against seven men - including two opposition Bangladesh Nationalist Party (BNP) figures - for their alleged role in the killing of Italian aid worker Cesare Tavella last year.
The 50-year-old was jogging in the capital Dhaka's diplomatic quarter when he was gunned down last September by unknown assailants.
The so-called "Islamic State" claimed responsibility for the killing but Bangladesh denies that the jihadists have a presence in the country.
Dhaka Police Chief Asaduzzaman Khan said the murder was intended to "embarrass the government" and prove the country was unsafe for foreigners. Tavella's murder was followed by a wave of killings targeting foreigners and secular bloggers and activists that were also claimed by IS and other Islamist extremists.
But on Tuesday, Sheikh Nazmul Alam, the deputy commissioner of Dhaka Metropolitan Police, said seven people had been charged with Tavella's murder, including two BNP opposition figures in exile.
Wave of killings
Investigators told Dhaka's "Daily Star "newspaper that BNP leader Mohammad Quayum - a university professor living in Malaysia - had planned the murder of Tavella as part of a conspiracy to create anarchy.
Quayum's brother Matin hired three killers to kill a “white man” and Tavella became their prey, the newspaper quoted officials as saying.
Police are yet to recover the firearms used in the shooting.
The criminal charges coincide with a nationwide crackdown on local jihadist groups. Police, under pressure to act on the spate of killings, have arrested more than 11,000 people.
But rights groups allege the arrests were arbitrary or aimed at silencing political opponents of the government.
Following the attacks against foreigners, international schools closed temporarily and embassies restricted their diplomats' movements, while Australia's cricket team cancelled a tour over security concerns.
After his name surfaced as the alleged mastermind, Quayum had told "The Daily Star" that he was being targeted because of his political activities.
jar/tj (AFP, PTI)