Four days after the murder of Savar schoolgirl Nila Roy, information about the dubious past of prime accused Mizanur Rahman (20) has started to surface. Mizan, who allegedly stabbed Nila in an abandoned house owned by his father on Sunday night, has turned out to be a member of "Shakil and Sakib" gang.

Members of the gang are infamous for extorting people and businesses, and often involve in stalking girls and drug trade, alleged locals of Savar's Dakkhin Para.

Speaking to The Daily Star, they said Shakil and Sakib are sons of Awami League joint secretary of Savar Municipality Shirajul Islam Shiru.

They said if any victim took the issues to Shiru, they would face stern warnings and even threats, which prevented people from protesting the gang's crimes.

Seeking anonymity, a victim who was beaten by the gang told this correspondent they came after him after he refused them extortion money.

"When I took it up with Shiru and demanded justice, he asked me to come over to his residence. I went there with my landlord. He confined us to a room and threatened us and forbade to talk about this with anyone," the victim said.

Meanwhile, a Savar local alleged that 10 hours before Nila's murder, Mizan and Shakib stalked another girl in front of the abandoned house. At one stage, Shakib even assaulted the girl.

Witnesses of the incident told this correspondent they could not protest fearing repercussions.

Some locals urged police to interrogate Shiru, which will bring everything to light.

Talking to The Daily Star at his residence in the same area yesterday, Shiru refuted the allegations against his sons, claiming that they are innocent. He said he does not even know who Mizan is.

He informed this correspondent that he is a cancer patient since 2015.

Asked about whereabouts of his sons, Shiru said, "I asked my sons to go into hiding as the neighbourhood became unsafe following the murder incident."

He also alleged that municipality Mayor Goni, his family and people from Jamaat and BNP have been harassing him for a long time. He claimed that they were trying to frame his sons in the case as a conspiracy against him.

Contacted, Hazi Abdul Goni, mayor of Savar Municipality and president of municipality AL, said he is yet to hear any such complaints against Shiru.

The mayor, however, said local AL did not invite Shiru to any programme because he had a bad reputation. He did not elaborate any further.

About the murder case, Saiful Islam, inspector (investigation) of Savar Police Station, said police are investigating it with highest priority.

Asked about locals' claims about Mizan's involvement with the Shakil and Shakib gang, the official said they are also looking for the duo.

The incident occurred on Sunday around 7pm, when Nila Roy (14), a 10th-grader of local Aced School, was on her way to a hospital with her elder brother Alok to have her respiratory problems examined. On their way, they were intercepted by Mizan, who threatened Alok and asked him to leave because he wanted to talk to Nila alone.

Mizan then forced Nila into the abandoned house, where he stabbed and left her. Upon hearing her cries, locals rescued and rushed her to Savar Enam Medical College Hospital. However, minutes after their arrival, doctors declared Nila dead.

The following day, Nila's father filed a case against Mizan and his parents. Police on Wednesday arrested one Selim Palowan (28), an associate of Mizan, for his alleged involvement in the case.