Seven accused of the murder case of retired Major Sinha were taken to Rapid Action Battalion-15 office in Cox's Bazar for questioning this morning.

A team of Rab-15 took them from Cox's Bazar district jail around 10am after completing official processes, reports our local correspondent quoting Mokammel Hosen, superintendent of the jail.

The seven accused include four members of police -- Assistant Sub-inspector Md Liton Mia, Constable Safarun Karim, Kamal Hosen and Abdullah Al Mamun.

Rab are, however, yet to take three top accused in the case -- including suspended officer-in-charge of Teknaf Police Station Pradeep Kumar Das and Inspector Liakat Ali -- in their custody for interrogation.

They were earlier placed on a seven-day remand each by a Cox's Bazar court but have been staying in the jail since August 6.

The other three are the witnesses of the two cases filed by police with Taknaf Police Station following the incident -- Nurul Amin, Nijam Uddin and Md Ayachh Uddin.

They were taken to Cox's Bazar Sadar Hospital for health check-up around 10:35am, said Saheen Md Abdur Rahman, resident doctor of the hospital.

The health check-up ended around 11:25, the doctor said, adding that no health issues were found during the examinations of the seven accused.

Meanwhile, the investigation officer in the murder case has been changed today.

Rab assistant director Khairul Islam, also senior assistant superintendent of police, will now investigate the sensitive and much-talked-about case, Ashique Billah, Rab's legal and media wing director, told The Daily Star.

"To change any IO (Investigation officer) of an individual case is an absolutely routine phenomenon," he said, adding that they decided to employ a much more experienced officer to investigate the case.