david mattingly has more. >> reporter: a fireball caught on camera and a devastating loss of life. but to those trained to investigate air crashes, the tragedy of mh 17 doesn't stop there. accusations of looting and possibly contaminating important evidence is disturbing. >> when you first saw that, what wednesday your reaction? >> the first thing i said was unrepeatable on tv. after that i was horrified. >> reporter: william walldock is a crash investigator and director of the investigation lab at embry-riddle aeronautical university. he says while it's pointing to a missile strike, investigators still need unaltered physical evidence to find the smoking gun, evidence you can't get from the black boxes. >> you still need the crash site. >> i'm firm believer that you follow the physical evidence. >> reporter: that's exactly what investigators did in 1996 in the case of twa 800 when it was suspected a missile may have brought the plane down, it wasn't until the wreckage was recovered and examined that it was determined there was no such evidence of an attack. walldock says a physica

>> david mattingly, thank you. >>> i appreciate you being with us, stacey. press allege that the couple told them that they looked up how hot a car needed to be to kill a child. there were internet searches by the mother and father. in court last week, the father defended their actions saying look, they just learned about a program about people leaving their kids in cars, that's why they did the search. when the mother saying, my god, he must have left the child in the car, do you believe her? should they be looking into her? >> absolutely. they are widening the investigation. they are doing that because of the comments, very odd off the chart comments that you wouldn't believe a mother would say when their child was found dead in the car. when the first thing that you ask is, did he leave the child in the car? something is going to arouse your suspicion. in the very beginning, while this case is opened up and investigation is going on, she wasn't honed in on right now after all these comments. she is going to be part of this investigation. a very big part o

>> no. >> reporter: david mattingly, cnn, miami. >>> and cnn gets unique access to a new york policerensic lab. we'll show you the state of the art equipment and how officers are using it to solve cases. the science behind the hunt, next. >>> bottom of the hour now. welcome back. i'm fredricka whitfield. >>> actor and comedian tracy morgan is back at home after being released from a rehab hospital center. had continues to recover from a car crash that left him critically injured last month. officials say a walmart truck rear-ended morgan's limo on the new jersey turnpike. the crash killed his friend and injured two others. morgan is suing walmart over the incident. >>> the federal government has doled out billions of dollars to people who don't deserve it. the money included payments for tax refuns and unemployment benefits to social security and medicare coverage that weren't legitimate according to a government watchdog agency. the mistake cost american taxpayers $106 billion last y r year. wow, sudden rush of hail the size of golf balls! pouring down on folks visiting a beach in r

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we sent david mattingly to a crash investigation lab to find out. >> reporter: what happens if a bombf right in the middle of a crash site like this? >> it's going to destroy an awful lot of evidence. it's going to move stuff around. depending on the size of the bomb, you may destroy everything we've got. >> reporter: you sound like you're resigned to the idea you're not going to get all the answers you would like to see from the crash site? >> personally, i don't think we're going to. >> and of course, the big risk is given the violence escalating that some sort of a bomb or missile could hit the crash site. what kind of information would they be able to get? that's the crucial information. we'll have david's report out front from that crash scene tomorrow. we look forward to seeing you then. in the meantime, have a good day. thanks for joining us. thanks for joining us. see you tomorrow night. -- captions by vitac -- www.vitac.com >>> good evening. thanks for joining us. welcome to a special extended two-hour edition of "360." breaking news out of gaza, international investigators m