>> in 1978, joseph sledge was convicted of murder in north carolina. >> they made me the scapegoat because they had no one to blame. >> at his trial, an fbi scientist testified that hairs found at the crime scene were 'microscopically alike' to joseph's. just months ago, joseph was released from prison, after serving almost forty years behind bars. dna testing had proved the hairs were not his. >> here's the hair from the defendant. here's the hair from the crime scene. i'm looking at them under the microscope and they have enough characteristics where i can say with reasonable scientific certainty that these two hairs match. >> they believed in what they were doing, but they were not scientists. it wasn't science at all. at all. >> joseph was at least the 74th american exonerated of a crime in a case involving the forensic science of microscopic hair analysis. >> it's not science to visually examine something and say they're the same. that's not science. that's subjectivity. >> the u.s. department of justice is now reviewing thousands of old convictions containing hair analysis testimony.

. >> in 1978, joseph sledge was convicted of murder in north carolina. >> they made me the scapegoatause they had no one to blame. >> at his trial, an fbi scientist testified that hairs found at the crime scene were 'microscopically alike' to joseph's. just months ago, joseph was released from prison, after serving almost forty years behind bars. dna testing had proved the hairs were not his. >> here's the hair from the defendant. here's the hair from the crime scene. i'm looking at tun

she conducted a test that led to joseph sledges exoneration. >> if you think about the way it is done on a hair, someone who is deciding what color is that hair. this is very subjective science, and dna is exactly the opposite. you have atcgt. in another sample you have atcgt, and you line them up next to each other there, is no gray area. >> when scientists figured out how to extract dna from hair in the late 1980s, the fbi stopped relying on hair comparison evidence, but by that point the bureau had introduced it at trials for decades. influencing thousands of convictions. >> fault lines airs tonight at 10:00 p.m. eastern, 7:00 pacific. fewer than half the americans have taken a vacation in the last year. why not taking a break can actually drag down cooperate profits. it wasn't science at all. >> there's a lot of lives at stake, a lot of innocent people. >> how many are still locked up? >> the integrity of the criminal justice system is at stake, plain and simple. >> "faultlines". >> what do we want? >> al jazeera america's hard-hitting... >> today the will be arrested. >> ground-b

. >> in 1978, joseph sledge was convicted of murder in north carolina. >> they made me the scapegoatse they had no one to blame. >> at his trial, an fbi scientist testified that hairs found at the crime scene were 'microscopically alike' to joseph's. just months ago, joseph was released from prison, after serving almost forty years behind bars. dna testing had proved the hairs were not his. >> here's the hair from the defendant.