"There are a lot of eye-witnesses and with inputs provided by those injured in the blasts we are trying to prepare the sketches of suspects, which will be released shortly," the DGP told reporters.
Investigators were working on some clues, he said. On February 21, two powerful bombs made with ammonium nitrate exploded in the crowded Dilsukhnagar area, leaving 16 dead and injuring 117. The state government has formed 15 probe teams.
The National Investigation Agency (NIA) is also probing the case.
No arrest has been made yet. But the DGP said police have "very valuable data available" and "it is a matter of time we will get a breakthrough".
"We are making rapid stride of progress and I am happy the way the investigation is going on," he said.
"There is perfect coordination between all the agencies and we are continuously getting lot of inputs."
He, however, said CCTV footage of the blast sites was not clear.
Reacting to a query, Reddy said interrogation of suspects was on.
When asked about the reported 'picking up' of some youths, Reddy said police were summoning them only for questioning.
"It may cause certain amount of inconvenience and they have to bear with it in the overall interest of the society," he said. "We have not yet come to any conclusion on involvement of any terror organisation," the DGP said.