A series of deadly attacks in Bangladesh has alarmed the international community - and there is little clarity on who carried out the attacks. BBC Bengali's Akbar Hossain examines the key questions behind the killings.
A series of deadly attacks in Bangladesh has raised alarm in the country and abroad - and there is little clarity on who is behind the violence. BBC Bengali's Akbar Hossain examines the key questions behind the killings.
The shooting dead of two foreigners in recent weeks has raised new security questions in Bangladesh.
How many people have been murdered?
Could Islamic State militants have carried out the attacks?
More than 20 people - including secular writers and bloggers, professors, members of religious minorities and two foreigners - have been killed in attacks blamed on Islamist militants since 2013.
The attacks on Italian aid worker Cesare Tavella and Japanese farmer Kunio Hoshi were similar in style and militant group Islamic State has reportedly said they carried out both attacks.
The killing of three people in two days in late April has heightened fears that the violence is escalating. The murders of two foreigners - an Italian and a Japanese man - last October, added a new dimension and more security questions.
However, the government quickly denied the presence of IS on its soil.
In many of the attacks, victims have been hacked to death with machetes, and in some cases beheaded.
Security sources believe Islamist extremist groups are behind the killings - but are sceptical about claims that IS is operating in Bangladesh.
Is the violence escalating?
Former Army Brigadier General Shakhawat Hossain, now a security analyst, says: "Every underground [Islamist] outfit has some sort of interconnection because they share the same ideology."
It appears so. Initially, secular and atheist bloggers and writers were targeted. But now the militants seem to be widening their list of targets.
A university professor killed on 23 April was not an atheist, but involved with cultural activities which many hardline groups condemn as "un-Islamic". This view reflects increasing radicalisation in Bangladesh, a secular Muslim-majority country where many show no sympathy for those perceived to be against their religion, even if that perception is without foundation.
The killing of a gay rights activist and his friend in Dhaka the day after the professor was murdered is seen as further evidence that the militants are broadening their list of targets.
Who is carrying out the attacks?
That remains murky - Bangladesh has myriad extremist groups.
The government has disputed claims by so-called Islamic State or al Qaeda-linked groups for the attacks, instead often blaming opposition parties or local Islamist groups it accuses of seeking to destabilise the country. These claims have been denied by the opposition.
After the killing of the LGBT magazine editor on 25 April, Prime Minister Sheikh Hasina said opposition parties "are involved with these secret killings as they want to destabilise the government and the country".
The attacks on Italian aid worker Cesare Tavella and Japanese farmer Kunio Hoshi last autumn were similar in style and reportedly claimed by IS.
But while the government says there is no organisational presence of IS in Bangladesh, many analysts say that matters little - because there are many local extremist groups which share the same ideology.
Former Army Brigadier General Shakhawat Hossain, now a security analyst, said last year: "Every underground [Islamist] outfit has some sort of interconnection because they share the same ideology.
"But I'm not sure whether Islamic State has any link to the foreigner murders."
"But I'm not sure whether Islamic State has any link to the foreigner murders."
Who else has been blamed for the attacks on foreigners?
Have the police caught any attackers?
Prime Minister Sheikh Hasina, who heads the Awami League party, has blamed the opposition Bangladesh Nationalist Party (BNP) for the murders of the two foreigners.
Four secular bloggers were hacked to death in Bangladesh last year, with each murder putting the spotlight on the government.
The BNP has denied the accusations, and says the prime minister's statement will hamper an independent investigation.
In October attackers attempted to slit the throat of a Christian pastor in Bangladesh's northern region. Police arrested five members of a banned Islamist group, Jamaat-ul Mujahideen, for the attempted murder. And a religious instructor in the Sufi strand of Islam - also known as a pir - was slaughtered at his home in Dhaka.
The police are under international pressure to find the killers.
But despite the lengthening list of victims the police have made little progress relating to the investigations. In only one case - the murder of blogger Ahmed Rajib Haider in 2013 - has anyone been convicted.
However, analysts say political instability is fuelling militant groups - and could affect the investigation.
But no one has been punished for the other killings.
Is there a link to other attacks?
In fact in many cases the police have been unable to identify the culprits. For instance, it has been more than a year since writer Avijit Roy was hacked to death. But no one has been convicted.
Four secular bloggers have been hacked to death in Bangladesh this year, with each murder putting the spotlight on the government.
Many analysts believe the police are not taking the investigation seriously because of Ms Hasina's comments, which include criticism of the atheist bloggers.
Other recent attacks have also sparked alarm in the secular, Muslim majority nation.
Last week, she issued a stern warning to anyone who criticised religion, saying: "I don't consider such writings as freethinking but filthy words. Why would anyone write such words? It's not at all acceptable if anyone writes against our prophet or other religions."
Last week, attackers attempted to slit the throat of a Christian pastor in Bangladesh's northern region.
The opposition say her accusations against them and the bloggers have hampered a credible investigation.
The police have arrested five members of a banned Islamist group, Jamaat-ul Mujahideen, for the attempted murder.
And the former Chairman of the Bangladesh Power Development Board, Muhammad Khizir Khan, was recently slaughtered at his home in Dhaka.
Mr Khan was a religious instructor in the Sufi strand of Islam - also known as a pir.
Two other pirs were murdered in their homes last year, and the assailants never found.
"Extremists even target people from their own religion who doesn't share same views with them," says political commentator Tareque Shamsur Rehman.
The different branches of Islam have traditionally co-existed in Bangladesh which is a predominantly Sunni Islam nation.
Although the victims of these attacks have very varied backgrounds - including foreigners and Bangladeshis, Muslims, a Christian, and atheist bloggers, police believe the attacks could be linked.
"The same group might be responsible for killing of bloggers and Islamic Pirs," said a senior police source who did not want to be named as he was not authorised to talk to the media.
That group may also have orchestrated the attack on the Christian pastor, "because the pattern looks identical", the source added.
Another police source suggested there could also be connections between the blogger and foreigner killings, although the killers may not be from the same group.
Police say a hardline Islamist group, Ansarullah Bangla Team, was involved in the blogger killings.
Some 10-12 people have been arrested for the four bloggers' deaths but they are not all necessarily directly linked to the group.
What's behind the rise in militant violence?
Details of those behind the spate of attacks is murky - but it is clear that militant groups are becoming increasingly active in Bangladesh.
Nobody knows how many radical Islamist groups are operating in the country, but one security source estimates there are 10-15 groups in existence.
Over the past year, the police have arrested more than 100 people, suspected of being involved with different Islamist groups.
They have also arrested around 20 people, including a British citizen of Bangladeshi origin, who were allegedly trying to "establish contact with Islamic State".
Mr Rehman believes that economic conditions are one factor motivating people to join extremist groups.
"Many people are living in poverty so it's easy to attract people to extremism in the name of religion."
However, Islamist militant groups are also reorganising to take advantage of political unrest in Bangladesh, Mr Rehman says.
"The government is spending more time cracking down on opposition activists rather than curbing militant activities."
Some Western countries have reservations about Shekih Hasina's government as the 2014 general election was boycotted by the main opposition alliance.
And for the first three months of the year, there was a blockade in many parts of the country as the opposition sought to put pressure on Sheikh Hasina to call elections.
More than 100 people died in the unrest that followed.
Former Brigadier General Shakhawat Hossain says that "Bangladesh should not ignore threat of militancy".
However, "the country needs political stability to fight it," he adds.
