The six visiting Interpol officials teaming up with the Criminal Investigation Department yesterday started forensic analysis of the computers and other computerised evidence related to the Bangladesh Bank heist.

"They started working from today [yesterday] in the CID's laboratory and are helping CID officials in computer forensic analysis," Additional Deputy Inspector General of CID Shah Alam told The Daily Star by phone.

"They all are technical persons with expertise in computer forensics. They will help only in forensic analysis of computers," he said.

Replying to a query, the CID official said the Interpol officials would neither investigate the bank heist nor visit Bangladesh Bank or other places. They will work basically inside the CID lab. "When a crime takes place through computers or using servers, the criminals delete and destroy a lot of evidence. It is [BB heist] a major incident in Bangladesh where assistance of experts from other countries is required. The Interpol officials will assist the CID officials to recover the evidence," said another CID official, asking not to be named.

On the first day of their three-day visit, the Interpol officials talked to the investigators and inspected the evidence gathered from Bangladesh Bank and elsewhere.

The team, led by Brad Marden, arrived in Dhaka onTuesday night.

On February 4, hackers stole $101 million from Bangladesh Bank's account with the Federal Reserve Bank in New York.

CID and BB officials said the $20 million sent to Sri Lanka was later recovered, while the rest $81 million went to Philippines.