Nightly News | April 17, 2013
>>> good evening. now the investigation in boston is moving. after a day of fits and starts and several false reports, it appears that from a mountain of evidence has emerged an image, a series of images ta likely show the bomber police are looking for. parts of boston are still shut down. it was another jittery day there after a bomb threat at the federal courthouse this afternoon. this is the bombing scene tonight. we have learned more about the devices themselves as this case, as we said, now picks up speed. while the fbi is urging caution and asking for patience especially from the news media, it appears they have pictures of their suspect. our justice correspondent pete williams has been following the investigation all day. he's in our d.c. newsroom tonight. good evening.
>> reporter: brian, good evening. the fbi is pursuing very promising leads. one in particular thanks to the abundance of pictures and videos. we are getting a close-up look at how the bombs were made.
>> guys, no way.
>> reporter: the fbi says it is getting what it asked for -- pictures from several sources showing someone carrying a heavy backpack or duffel bag and a placing it at the spot where one bomb went off. one of the most promising images, they say, comes from a department store surveillance camera high up on a building, able to look down at the crowd. on a day when incorrect news reports of an arrest distracted officials, investigators were working aggressively to discover, find, and interview that person. that's at the scene of the second bombing following the first by about 15 seconds. it's that second spot shown on oh this picture sent to nbc station whgh showing a garbage bag next to a trash can. federal officials tell nbc news that is the spot where the second bomb went off. formerer atf bomb investigator jim cavanaugh said it is obvious to him looking at the pictures.
>> large injuries were on the side of it. debris field to the left. some protected areas over on the right side that indicate the blast was to one side of the trash receptacle . this was the scene of the blast.
>> reporter: we are seeing close up photos showing the pressure cookerer deformed by the blast, one of its lids blown to the top of a nearby building. the they are a favorite because pressure builds up before it is released. investigators begin to trace down where components wr brought because they know the makerer of the pressure cookerer, the batteries used, made in china but widely available, and the type of wire used to hook the main components together. bomb technicians are examining two electronic components included in the bomb to see whether they were parts of timers or receivers for a remote detonation signal. all potentially promising leads, says a bomb expert.
>> it depends on how unique the bomb components are. how identifiable the characteristics are. what other forensics involved in that whether it be fingerprints or dna, et cetera .
>> reporter: investigators are optimistic that they are close to the answer of who did this and why in an investigation that's moving very rapidly on several fronts.
>> about that rapid speed and optimism, pete williams , thanks. we