The CBI on Saturday sent the two mobile phones of slain Congress councillor Tapan Kandu and his nephew Mithun for forensic tests.

The decision assumes significance in the backdrop of his family's allegation that the inspector-in-charge of Jhalda police station Sanjib Ghosh had called up on these two numbers several times asking Tapan, who was murdered on March 13, to join Trinamul.

Mithun alleged that a few days before the murder, he received a call from Ghosh asking him to convince Tapan to switch to Trinamul.

“The police officer also offered my uncle the post of vice chairman if he agreed. Ghosh also threatened to frame charges against my uncle if he didn’t,” alleged Mithun.

An audio clip of a purported conversation between Mtthun and Ghosh surfaced on social media a day after Tapan was shot dead on March 13 at Jhalda. The CBI also collected the audio clip and sent it for forensic test.

The CBI summoned Ghosh over phone to come to its temporary camp for interrogation. The officer is yet to respond. Sources said he told some of his close aides that he will not turn up for interrogations until summoned in writing.

As the role of the police in the Tapan Kandu murder has been a talking point, the CBI interrogated the subdivisional police officer of Jhalda Subrata Deb for an hour on Saturday. The SDPO is part of the special investigating team that Purulia police set up to probe the murder.

The CBI sleuths interrogated the five policemen who were taken off duty and sent to police lines by the police as punishment after the murder for dereliction of duty.

Sources said the five cops were checking vehicles at a Naka checkpost barely 100m from the place Tapan was murdered but did not reach the spot soon. Sources said the driver of the police vehicle told the CBI that an officer present asked him not to move when he started the ignition of the vehicle on hearing the commotion. The CBI will interrogate the driver and the officer together, the source added.

Tapan’s wife Purnima, also a Congress councillor, on Saturday sent an email to the Purulia district police chief alleging that the additional SP and other policemen were harassing her.

Purnima said that on the day the civic board was formed at Jhalda municipality she and three other councillors had gone to take oath. “When we were entering the municipality office the policemen stopped us. When I tried to proceed further they assaulted me... I could recognise the additional SP," Purnima wrote, seeking action against the police officers.

She also sent a video clip of the alleged assault to the SP.

SP S. Selvamurugan said they are inquiring into the complaint.

Police lodged a suo motu case against four Congress workers, including councillor Biplab Kayal, for attacking policemen on duty and blocking public roads on the day of formation of the civic board. The Congress workers on that day had observed Black Day.