Patna: The CBI is learnt to have issued notices to six persons, including a former station house officer (SHO) of Muzaffarpur town police station, to interrogate them in connection with the mysterious disappearance and subsequent murder of 14-year-old Navruna Chakravarty.

The notices came in the backdrop of interrogation of six accused persons who were arrested earlier in the case on April 29 this year. The CBI on Tuesday produced the accused in the special CBI court in Muzaffarpur, as their three-day police remand in the case came to an end.

The CBI requested the court to extend the remand for three days as their interrogation was incomplete. The court agreed to the CBI's request and allowed the investigating agency to interrogate them for three more days. The CBI reached Patna with the six accused.

Sources in the CBI said Jitendra Kumar and Amit Kumar who were appointed as investigating officer in the case lodged with the Muzaffarpur town police station after the disappearance of Navruna, a Class VI student, from her Jawaharlal Road residence on September 18, 2012, have been summoned for questioning.

While Amit was posted as sub-inspector, Jitendra was inspector-cum-station house officer of town police station when the incident occurred. Four others involved in property deals have also been served notices asking them to be present in the Patna office of the agency.