jim maceda has been following the story live. i guess the question is what is the latest on the investigation? and do you see evidence of that increased security force? >> reporter: hi, richard. nice to be with you from sochi. police now believe it was a male suicide bomber who set off sunday's bomb just inside volgograd's train station. he's been identified by several news sources to be a 26-year-old russian named pavel, a medical school graduate who converted to a radical and violent form of islam. now, you'll recall, richard, there was speculation early on that a female suicide bomber had set off that first bomb. investigators are now running dna tests to confirm that i.d. on monday sayed they they'd found links between the two bombs, specifically on the similarities of the explosives