Four members of the banned militant cohort Jama’atul Mujahideen Bangladesh (JMB) have been involved in killing Rajshahi University professor Rezaul Karim Siddiquee, claimed Rajshahi Metropolitan Police Commissioner Mohammad Shamsuddin.He said this at a press conference at his office on Tuesday afternoon.Three people hacked Rejaul to death while another was waiting on road with a motorcycle, he also said.Mohammad Shamsuddin said police held Maskawat Hasan Sakib alias Abdullah from Gaibandha on Sunday night.Maskawat confessed on Monday his directly involvement in the killing before the court, said the commissioner.The RMP commissioner said police also seized the motorcycle from Khorkhori area of the city on Monday night and held three persons for their alleged involvement in the murder.Prof Rezaul Karim, 58, of the RU English Department, was killed by miscreants in the city’s Shalbagan area while he was waiting for university bus on April 23.