But the style of the attack has surprisingly been the same.
Upper parts of the body, particularly head and neck, were the main targets of these attacks.
'Hit to kill' seems to be the motive.
The head that throws up the challenge to radicalism must fall, it seems.
Involvement of militants in the murder of Rajshahi University teacher Yunus was proved in the court and two of them were convicted.
Militants are facing trials in the murders of Prof Humayun Azad of Dhaka University and for Haider's murder as well.
Police said blogger Mohiuddin survived as he was clad in thick winter clothes during the attack.
Recently-slain Rajshahi University Prof AKM Shafiul Islam was attacked in a similar style and his son claimed that militants were involved in the killing. They went for his head with sharp weapons.
The bloggers were attacked for writing against Islamist radicalism and for promoting the cause of Bengali linguistic nationalism that led to the creation of Bangladesh.
Professors Yunus and Azad were also against militancy while Prof Islam was an admirer of Lalon Shah whose syncretic philosophy is considered anti-Islamic by the radicals.
Only a month ago Ahle Sunnat Wal Jamaat leader Nurul Islam Farooqi was slaughtered at his house in Dhaka. His family blamed Islamist militants for the killing.
Blogger Ashraful Alam was also butchered at his house, while blogger Haider and Profs Yunus, Azad and Islam were attacked at lonely places.
Prof Azad came under attack near Suhrawardy Udyan in Dhaka on Feb 27, 2004 when he was walking towards the TSC from Ekushey book fair.
Azad survived the attack that time as he was instantly rushed to hospital, but died in Munich, Germany later on Aug 11, 2004. Police pressed charges against militants over the murder.
Most of the other victims, however, died of profuse bleeding after the attacks.
Haider was attacked at Kalshi in Dhaka’s Mirpur last year -- only 10 days after the Ganajagaran Mancha began its Shahbagh-based agitation.
The charge-sheet in Haider murder case says one assailant slashed at his neck with a sharp weapon and then others swooped down on him.
Prof Islam was attacked in the head and neck on Nov 15 at an isolated place near the Rajshahi University campus. Doctors at Rajshahi Medical College Hospital said he died of bleeding.
Prof Yunus was murdered near the same place 10 years back in 2004 early in the morning.
Though militants were arrested by law enforcers with firearms and explosives in their possessions on several occasions, they are using sharp weapons for these select targeted assassinations.
Militants drew huge attention in 2001 during the BNP-Jamaat alliance government with the rise of Siddikul Islam aka ‘Bangla Bhai’, Sayekh Abdur Rahim and their cohorts. The Khaleda government at that time, however, was denying their rise.
Later in 2005, militants were involved in serial explosions across the country to prove their presence.
The Jamaat-ul-Mujahideen (JMB) that claimed responsibility for the explosions is now said to have created a network of bomb making facilities and hideouts in neighbouring West Bengal.