With investigators trying to put together pieces of evidence, nearly 40 people have been questioned by police and central probe agencies for their suspected role in the twin blasts in Hyderabad.
Official sources said 30 to 40 people have been interrogated by sleuths of Andhra Pradesh Police, National Investigation Agency and other central security agencies in connection with the Thursday's blasts which claimed 16 lives and injured over 100.
Investigators are also verifying reports that five people, who checked into a lodge at Dilsukhnagar, left just before the blasts or immediately after the explosions.
Out of the five people, two have turned out to be innocent. One had checked into the hotel under a fake name. He had checked out a few minutes before the blasts which led to the police to term him as a suspect, the sources said.
During questioning, he told the police that he had checked in with a friend and wanted to keep his identity a secret. The police on verification found that his statement was correct and let him and his friend go.
However, verification of three other persons, who had left the hotel around the time of the explosions, was still on, sources said.
Meanwhile, Union Minister of State for Home R P N Singh said all evidence collected from the ground have been sent for forensic examination and nodal agencies were looking into them.
"Whatever evidence the agencies have been collected, all have been sent for forensic examination. There are leads and we are looking into the leads," he told reporters here.
The minister said since investigation was still on, no details could be shared.
"At the moment we are not sharing in detail but the perpetrators of this barbaric act will be caught and strictest punishment will be given," he said.
According to sources, the video footage obtained from the site of the blasts showed that three persons were found moving suspiciously near bicycles strapped with explosives, just minutes before the explosions.
Help of experts was being taken to enhance the footage for clarity.