The search for the new suspects began after the RAB received DNA Lab report from the USA, RAB sources said.
Mohiuddin Ahmed, Assistant Superintendent of RAB's Investigation and Forensic department and the investigating officer of the case, on Tuesday, submitted the progress report to the chief metropolitan magistrate court in Dhaka.
“In addition to the conventional investigating method, we are taking help from the highest technological and scientific resources from the USA. We are now analysing the report we received from the US Lab,” he told reporters.
The couple's only child Mahir Sarwar Megh was found in the apartment. The autopsy report said the couple died of wounds inflicted by sharp weapons possibly by amateurs.
Eight suspects were arrested in the case, but police failed to make any headway in five years so far. Five of the suspects were, however, accused of another murder.
The CID was first given the responsibility to investigate the case. But, after they had failed to make any progress in two months, the case was transferred to the RAB.
The court has extended 47 times the date of submitting the final investigation report. The court has now scheduled May 2 for submission of the report.