captioning sponsored by wnet >> sreenivasan: on this edition for sunday, april 10: investigators reveal: the terrorists who attacked brussels last month originally intended to strike paris. in our signature segment, a new path in texas to appeal convictions based on flawed scientific evidence. >> junk science has proven we have numerous people, maybe large numbers nationwide, wrongfully convicted. >> sreenivasan: and, watching" the wire" in the classroom. next on pbs newshour weekend. >> pbs newshour weekend is made possible by: lewis b. and louise hirschfeld cullman. bernard and irene schwartz. judy and josh weston. the cheryl and philip milstein family. the citi foundation. supporting innovation and enabling urban progress.

the john and helen glessner family trust. supporting trustworthy journalism that informs and inspires. sue and edgar wachenheim, iii. corporate funding is provided by mutual of america-- designing customized individual and group retirement products. that's why we are your retirement company. additional support has been provided by: and by the corporation for public broadcasting, and by contributions to your pbs station from viewers like you. thank you. from the tisch wnet studios at lincoln center in new york, hari sreenivasan. >> sreenivasan: good evening and thanks for joining us. belgium announced today: isis terrorists hurried to carry out suicide bombings on the airport and a train station in brussels and had originally intended to attack paris, again. without providing plot details, belgian prosecutors said" numerous elements in the investigation have shown that

the terrorist group initially had the intention to strike in france again. eventually, surprised by the speed of the progress in the ongoing investigation, they urgently took the decision to strike in brussels." the brussels attacks killed 32 people on march 22 and came four days after the arrest in brussels of salah abdeslam, the prime suspect in the november attacks in paris, which killed 130 people in cafes and a concert hall. belgian police detained four more men this weekend for the brussels attacks, including mohamed abrini, who they say, has admitted being "the man in the hat" alongside two bombers in brussels airport security video. he's also charged in connection with the paris attacks in november. in india, a celebration of the hindu new year turned tragic today. a fireworks display sparked a fire and explosions overnight inside a packed temple complex in the southern state of kerala. most of the 102 people who died were killed when a building storing fireworks collapsed. indian prime minister narendra modi visited the site and met with survivors at a hospital

where some of the 400 injured were being treated. greece is condemning macedonia's use of force today against migrants and refugees stranded by border closures throughout europe. macedonian soldiers fired tear gas to stop migrants from scaling the fence separating the two countries. doctors without borders said it treated 300 people for tear gas and injuries. more than 11,000 migrants, hoping to pass through to western europe, are camped at that border inside greece. the presidential campaign calendar is now clear until new york's delegate-rich primary on april 19. texas senator ted cruz swept all 34 of colorado's delegates at yesterday's republican state convention and friday's caucuses, but he still trails businessman donald trump by 226 delegates in the race to the 1,237 needed to win his party's nomination. vermont senator bernie sanders won the wyoming caucuses yesterday but split the 14 delegates there with hillary clinton. sanders has narrowed her lead in pledged delegates-- those awarded by winning votes in

primaries and caucuses-- to 219. but clinton has an advantage of 438 superdelegates-- party officials who get a seat at the national convention-- putting her ahead by more than 650 delegates overall. looking to his remaining nine months in office, president obama told fox news today he hopes to find common ground with republicans in congress. >> our system is designed to work if people who disagree can listen to each other, if we treat each other fairly in terms of the process, if we recognize that compromise is not a dirty word. >> sreenivasan: the president also said he believes mrs. clinton did not jeopardize national security by using her private email server while serving as his secretary of state. >> sreenivasan: a virginia man who spent 33 years in prison for

murder and rape was exonerated and released friday, with prosecutors saying the scientific evidence used to convict him would not result in a guilty verdict today. defense attorneys had argued experts were wrong to match bite marks on the rape victim's legs to the defendant and that bite marks are too unreliable to use in court. this argument underscores a new law in texas, the nation's first, to assist prisoners in appealing convictions based on unsound scientific evidence, sometimes called "junk science." in tonight's signature segment, special correspondent alison stewart went to texas to see how that law is working. >> i grew up with him from a baby. and i adored him. he was kind of eccentric. he had his flaws. but, oh my god, he was a good man. >> reporter: sonia cacy is describing her uncle, bill richardson. in the early 1990s, cacy lived in fort stockton, texas with her uncle, who was in his seventies and suffering from a form of dementia.

on the morning of november 10th, 1991, everything changed. >> the night before we watched a movie together. burt lancaster was in it, and that was my favorite. and then when that was over, it was a late movie, i went to bed, and we were both alive. >> reporter: around dawn, a fire broke out in their home. the then 44 year old cacy escaped through a window and ran to a neighbor, who called 911. when emergency responders found richardson, the 76-year-old man was dead. authorities said the fire was suspicious. when did you sense, sonia, that the authorities suspected you of setting the fire? >> well, they took me to the hospital. i was there eight days for smoke inhalation. scraped all my fingernails. i said, "what's the matter? what are you looking for?" and i was still crying over uncle bill. and he said, "blood or whatever's on you." >> reporter: five months later, cacy was arrested and charged

with murder by arson. did you have anything to do with the fire that occurred on november 10, 1991? >> no. i did not. i did not ever, anything. no. >> reporter: gary udashen is cacy's attorney. >> they claimed that she had doused her uncle bill, in gasoline and set him on fire, which killed him and then burned the house down. >> reporter: at the trial, the most critical piece of information came from a report by a toxicologist, someone trained to check for drugs and chemicals in the body. he testified that accelerant was found on richardson's clothing. the prosecution's fire investigator also testified that burn patterns in the house were indicative of an accelerant. >> sonia is a real, live example of somebody whose life was really destroyed based upon bad scientific testimony in court.

>> reporter: in 1993, cacy, a wife and mother of three grown children, was convicted in a jury trial and later sentenced to 99 years in prison. but a relatively new texas law could change cacy's life. it's known as the "junk science law." the law offers a direct path to appeal when there is scientific evidence that was not available at the time of the conviction or there is new evidence that contradicts what was used to convict. before the law, it was impossible in texas to appeal a conviction based only on flawed scientific evidence. when the innocence project of texas took cacy's appeal, attorneys immediately questioned the toxicologist's results, specifically a chromatography test, which separates mixtures found at crime scenes to detect molecules like those from gasoline. >> we actually had the texas state fire marshal, who's a state of texas official, issue his report where he said the cause of the fire should be listed as a "undetermined." and what he meant by that, that

there was no gasoline on the clothing. so you couldn't say that it was arson. dr. buc is the expert that the district attorney hired. >> reporter: which backfired. >> which backfired, because dr. buc said that the chromatograms are "negative for gasoline," which is exactly what all of our other experts said. > reporter: seven other arson experts brought in by the defense agreed, and two defense pathologists who reviewed richardson's autopsy found he died of a heart attack, not burns. >> what everybody thinks most likely happened is that uncle bill was a very careless smoker. he accidentally set the house on fire, and he actually died of a heart attack. >> reporter: this new interpretation of the evidence convinced the texas board of pardons and parole to grant cacy parole, after she had spent five years in prison. but without her conviction overturned, at 68, cacy has been required to report to a parole officer once a month for the past 17 years.

>> reporter: what kind of burden has it been to be considered in the eyes of the law a convicted murderer? what has the burden of that been? >> it's a big burden, because you can't even get a place to live. everybody does your background. where you're living, where you're going to work. i've never been able to get a place to live. you know, a regular place. >> reporter: today, cacy lives in southeast texas and spends time with her family and friends. but her standing murder conviction makes it difficult to find a job because of background checks. she's gotten by working for friends and pet sitting. cacy hopes the junk science law will bring her a step closer to real freedom. >> it's definitely a law-and- order state, but we've gotten smart. >> reporter: democratic state senator john whitmire, who chairs the texas senate criminal justice committee, sponsored the junk science bill. he says his state's reckoning with d.n.a. testing paved the way for the law. since 1993, texas has exonerated

57 people, mostly convicted of murder and sexual assault, who appealed with d.n.a. evidence. the highest number of any state. whitmire says that was a moral wake up call. >> i hope it keeps everybody up at night if they think one person is wrongfully convicted. junk science has proven we have numerous people, maybe large numbers nationwide, wrongfully convicted. >> reporter: when texas adopted its junk science law in 2013, it was the first in the nation. last year, california, became the second. junk science appeals are finally making it onto court calendars in texas, but there is no deadline for decisions. >> reporter: so far, only one case has resulted in a new trial. a handful of other cases, including sonia cacy's are waiting to be heard. >> reporter: but the number is expected to increase, because of the work of the texas forensic science commission, a group of seven scientists and two attorneys appointed by the governor. they investigate the integrity of forensic analysis at crime

labs and set guidelines about what is solid forensic science for judges, who ultimately decide what evidence a jury sees. in february, the commission recommended that bite mark evidence should stay out of courtrooms, because there is not enough scientific research to prove its validity when identifying a perpetrator. the commission is also reviewing other types of evidence, like microscopic hair analysis, that involves comparing under a microscope a loose hair from a crime scene to hair from a suspect. cases that use the junk science law hope to end up here at the texas court of criminal appeals. it is the body that can overturn a conviction. but an overturned conviction is not an exoneration. it's an important distinction, and it's where some say this law falls short. criminal defense attorney jeff blackburn pushed for the law. he previously worked for the innocence project of texas and today has his own practice. >> are you going to get exonerated? probably not. that means you're not going to be compensated.

that means you're never going to really have your name cleared. you're never really going to get the moral or practical satisfaction of saying, "i didn't do it and the courts have exonerated me." and that's an awful big deal. >> reporter: for instance, in that first case where the conviction was overturned due to doubts raised about junk science, the defendant was not exonerated or declared actually innocent. which requires a higher standard of evidence. blackburn says one of the law's shortcomings is there is no accountability for mistakes. >> the worst thing under this law is that now prosecutors get off easy. they have an excuse and they can say, "well, i guess it was just those creeps in the lab coats that did it to us this time. sorry." that prevents us from ever understanding what really goes on in these cases. >> reporter: senator whitmire points out that it took the state legislature three sessions to pass the bill. we talked to a couple of attorneys who felt that the law didn't go far enough, because

there wasn't an exoneration clause in that. >> you probably couldn't pass that. >> in my work, in criminal justice in texas, i take three steps forward, and they pull me back two. so at the end of the day or end of session, i've taken a step. >> reporter: the current district attorney of the county where cacy was tried stands by her conviction, rejects her arguments about the scientific evidence, and says there is considerable circumstantial evidence that still points to her guilt. what are you going to do if sonia prevails under the junk science avenue, but is not exonerated? >> i just don't see that happening. >> reporter: are you sure you're giving her false hope? >> no. >> reporter: you feel that confident? >> i feel that confident that she's going to be exonerated. >> reporter: cacy thinks often of her uncle bill while waiting for her new day in court. >> my hopes for the future are to get everything like this over with, and to be exonerated before i die.

and it would be really nice for my children. >> sreenivasan: see examples of how controversial science has led to convictions. watch our video online at facebook.com/newshour. >> sreenivasan: looking beyond the lead-tainted drinking water crisis in the city of flint, michigan, an associated press investigation of environmental protection agency records has found: nearly 1,400 water systems providing tap water to nearly four million americans exceeded the acceptable lead level at least once between 2013 and 2015. a.p. reporter meghan hoyer co- wrote the story, "tainted at the tap," and joins me now from washington, d.c. how wide-ranging is this? is this every part of the country gee graphically, size of cities, big and small? >> it is. what we found were, we looked at

roughly 77,000 water systems across the u.s and what we found was you know, the ones that had lead levels higher than the federal standard ranged, they were in almost every state, and they ranged from very small systems with 20 or 25 customers to very large systems. we saw cities and counties that served hundreds of thousands of people that had repeatedly brch over the limit. >> sreenivasan: and you also point to the fact that the notifications were different from town to town and how people felt like whether they really knew that there was a danger or not, differed. >> so when a system is over the federal lead limit, it has 60 days to put out a notification to its customers telling them there has been lead found in the water. what we found were those notifications were often written in a way that was confusing to customers, where customers didn't understanded severity of the problems. they were told to run their

water for 30 seconds to two minutes and that would flush a lot of the read out of the water. they were told that the systems were aware of the problem and were working forward it but a lot of these systems had had problems for years and years. >> the recent story focused in on galasberg, illinois. one of the things you highlight is there seems to be a gap between when the epa coming up with the tests and counter-- county leadership and what they can do about it. >> there was a real disconnect from what we found in the water systems versus what health departments were looking at. basically they're focusing on things like lead paint in homes and lead in toys. but they're not even looking at the water system, oftentimes as a source of some of these problems. and there's been more of a push now nationally to get water systems and health officials working more in comfort on these kinds of issues. >> sreenivasan: given that the absolute solution is to go ahead and rip out all of the pipes and put in new ones, that say

multibillion, trillion dollar type of problem. so where do the cities stop with their responsibility and where does the private owner of the water or the recipient of the water, where does their responsibility start? >> the problem with most of these water systems is not the water main itself or the water supply, it's those pipes that lead from your water main to your house or to your business. and that is mostly on the homeowner or the business own tore replace. a lot of cities and counties are doing some work to try to fund some of this replacement. they're offering interest-free loans or grants to homeowners. they're doing some of the work themselves. but this is an extremely expensive problem that's going to take years and years to fix. >> meghan hoyer of the associated press, thanks so much for joining us. >> thank you. >> sreenivasan: one of the most

critically acclaimed tv drama series in recent years is "the wire," which ran on hbo for five seasons until 2008. the show has found a steady stream of new viewers in recent years, and has even made it to college classrooms, where it is viewed as much more than a hollywood production. for these college students, homework includes watching a tv show. >> "the wire" just begged for all kinds of social, political, cultural analysis. >> when we were watching the show together, we both kept thinking, "this would be great as a class." >> sreenivasan: sociology professor sherriann butterfield and literature and gender studies professor fran bartkowski are co-teaching this 15-week course based on" the wire" at rutgers university in newark, new jersey. the crime drama set in baltimore, tackled a different aspect of the city's problems each season; from how gangs function to how the political class, and the press enable the problems to grow. >> even though it's a fictional show, you can't help but to not

feel sad for how these things end when you realize if there was some change in the system, things might be different. >> sreenivasan: the fourth season of "the wire" focused on middle school students who are recruited to sell drugs. >> first we're gonna give you the corner up on payson. it used to be bodie's old corner. >> some school systems say that kids don't want to come to school and learn. i like how they look at their backgrounds and show why they come to school and act the way that they do. >> sreenivasan: this is the second time butterfield and bartowski have taught this class. but it's not just this college, new york university, johns hopkins, and harvard have used" the wire" as teaching material. the professors shared their experiences teaching "the wire" at a conference this weekend at columbia university. english literature professor eileen gillooly organized it. >> it shows up in evidence classes in law schools. it shows up in african american classes on masculinity,

sociology classes, anthropology classes. it's just, you name it, it shows up there. >> sreenivasan: gillooly drew comparisons between "the wire" created by david simon and 19th century novels. >> it really is like a text. it's so carefully put together. it repays reviewing, the way a good text replays rereading, so every time i read "the iliad" or "bleak house" or "david copperfield," or whatever i see more and more. >> sreenivasan: you're putting david simon with some pretty high company? (laughing) >> well, i suppose if tv is coming into its own as genre, he'd be one of those people that's making it come into its own. >> sreenivasan: this semester the rutgers class is using the show's portrayal of racial inequality as a springboard to analyze the "black lives matter" movement. >> black lives matter came as a movement because some people believed they'd hit a ceiling,

like, we are done with this. >> it's not just about people getting shot and killed. it's the injustice that happens after their civil rights have been violated. >> whether you agree with how it gets portrayed or not, that lends itself to great levels of debate and engagement. the students find themselves caught between, "well, i thought i knew what i would've done before seeing this show, and now that i see the interconnectedness of systems, i'm not sure how i would've handled this." >> sreenivasan: you don't walk away saying, "i see what the fix is." >> right. there is no fix. >> sreenivasan: bartowski says it's possible she will teach" the wire" again. >> i have certainly asked myself, and people have asked the question of would you, you know, are there other shows that you would teach? and there might be a couple. but none of them are quite as complex and rich, i think, as this is and remains.

>> this is pbs newshour weekend, sunday. >> sreenivasan: walk into certain gourmet grocers or high- end restaurants, and you might find truffles on the menu. truffles, a kind of fungus, grow underground and are difficult to harvest, which is partly why they fetch a high price on the open market. and for one group of people in war-torn iraq, truffles are a way to help make ends meet. the newshour's zachary green has more. >> reporter: on a typical morning on iraq's mount sinjar, mata mahmoud and his companions are hard at work, looking for truffles. mahmoud and his friends are ethnic yazidis, a religious minority in iraq who have been persecuted by islamic state militants, who overran this region in 2014. like many in his community, mahmoud was displaced from his home. >> ( translated ): my house is in the hands of the islamic state. they didn't leave anything for us. they destroyed and blew up our houses and now this is our only source of income. we have no salary, and we feed

our families with this. >> reporter: finding and digging up the truffles is difficult and dangerous work. >> ( translated ): there are lots of i.e.d.'s, the islamic state has planted a lot. my friend was blown up by one over there in the west. the islamic state is also shooting mortars and they land very close by. >> reporter: with his harvest in hand, every morning, mahmoud and other yazidis go to this local vegetable market to sell truffles to traders like this man, who will then ship them as far as baghdad. >> ( translated ): today i have bought 700 kilos so far, and i hope to reach a ton. and by sunset i'll be done. >> reporter: on an average day, mahmoud sells about three kilograms, or about 6.5 pounds of truffles, earning around 10,000 dinars, or roughly eight u.s. dollars. despite the hardship and the danger, many yazidis are still thankful for the work. >> ( translated ): it's a blessing from god. these poor people don't have a dinar in their pocket and when they work from sunrise to sunset they make 50,000, 60,000, even 100,000. it's a gift from god.

>> sreenivasan: finally john kerry will be the first sitting u.s. secretary of state to visessity and lay flowers at the peace memorium museum at hiroshima in japan commemorating the atomic bombing that hastened the end of world war ii in the pas sifnlgt he is not expected to apologize for the truman's decision to use new clear weapons on an enemy. kerry is in gentleman an attending a two-day meeting with the group of 7. on the nursehour tomorrow. nick shifman continues his series inside kenya with a look at the impact of corruption on life there. that's it for this edition of pbs newshour weekend. i'm hari sreenivasan. have a good night.

captioning sponsored by wnet captioned by media access group at wgbh access.wgbh.org >> pbs newshour weekend is made possible by: lewis b. and louise hirschfeld cullman. bernard and irene schwartz. judy and josh weston. the cheryl and philip milstein family. the citi foundation. supporting innovation and enabling urban progress. the john and helen glessner family trust. supporting trustworthy journalism that informs and inspires. sue and edgar wachenheim, iii. corporate funding is provided by mutual of america-- designing customized individual and group retirement products. that's why we are your retirement company. additional support has been provided by: and by the corporation for public broadcasting, and by contributions to your pbs station from viewers like you. thank you.

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