help. i am an example of that. that i came forward and i tried to do the right thing. >> reporter: we also learned today, omar mateen entered the pulse nightclub in orlando at least once before he started his massacre. scott, law enforcement forces tell us, mateen got a wristband which enabled him to come and go when he wanted. he left at one point. returned two hours later and started shooting. >> david begnaud, thanks. >> well, isis is losing its grip on the iraqi city of falluja, fighting there continues. a major test of whether the u.s. supported iraqi government can reclaim iraq from isis. isis held the city of 300,000 people for two years and now a u.s. military adviser says,

about a third of fallujah is secure. charlie d'agata has been covering the battle. >> reporter: iraqi gunners fired towards isis machine gun positions near the heart of the city. the militants retaliated with mortars as a column of iraqi humvees inched forwards as residents still trapped inside fallujah scrambled to get out. tank commander, abdullah al shambra told us the isis tactic of hiding among civilians slowed his progress. it is hard to thread the needle with a tank. >> i can't kill the children. i can't kill the old womens. you know, all of them, like my father, my grandfather, my sisters. >> reporter: advancing soldiers face what one commander called a spider's web of home made bombs. and nests of snipers. one bullet tore through the leg of soldier hider mowein abbas

who seemed more anid noyed he h to stop fighting. >> the soldier walked into a boobytrapped house, a bomb went off. he didn't make it. >> reporter: these iraqi special forces just finished 17 days of intense urban warfare. what was the most difficult part of it? "the street by street fighting is tough he said. so we decided to fight like them and now we are beating them at their own game." as the sun begin to sink we found a group of hungry young soldiers settling down to their first meal all day. battle-hardened, weary having driven isis out of two other cities it is a brief respite as the the fight for fallujah drags on. today, the u.s. state department pledged another $20 million in humanitarian aid skop , scott ts

those who fled the city since the assault began last month. now in urgent need of food, water and shelter. >> charlie d'agata back from the battlefield and in london for us tonight. charlie, thank you. >> coming up next -- is federal policy hindering efforts to protect children from lead? >> and later, a rescue at the bottom of the world.

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a little touch is all it takes. k-y touch. we have done a good deal of reporting about lead in the water of flint, michigan. well tonight dean reynolds is looking at a greater danger to children, lead paint.

used in homes for decades. we were surprised to learn that the federal government is aware of lead in homes that it rents to the poor. but it has a policy of waiting until a child is harmed before it gets the lead out. >> reporter: over the course of his difficult life, 6-year-old mchale mcmullin had his blood tested more than 30 times. >> come on. >> reporter: and it's never been easy. it has been a routine ever since elevated levels of lead were found in mchale's blood. when did he start having health problems? >> around 16 months. >> what will we play, simon says? >> yeah. >> reporter: nowadays he is a slow learner with a speech impediment and attention disorders. tolonda mcmullin is his mother. do you feel betrayed? >> yes, i feel betrayed. i feel robbed. >> reporter: because almost

everywhere she lived in chicago it is in subsidized housing where lead based paint is a common threat. the department of housing and urban development provides subsidies for them and other poor families across the country but hud regulations say a child must actually be lead poisoned before any repairs are required or moves approved. more than 2.5 million, h.u.d. subsidized homes have hazardous levels of lead, but h.u.d.'s measurement of danger is four times higher than what's recommended by centers for disease control. h.u.d. which declined our request for on-camera interview pro posed to bring its standard into line with the tougher cdc position but regulatory review takes a long time. >> deteriorating. >> reporter: when he visited the mcmullin's, chipping, lead based paint was easy to spot at the home threshold. a law professor at loyola university and the mcmullin's

attorney. >> in federally assisted housing, families are forced to choose between lead poisoning and the brain damage it causes or homelessness and life on the streets. >> reporter: a few weeks ago, tolonda mcmullin chose homelessness. she and mchale, moved to a shelter june 3rd and are now hoping h.u.d. can find them a safe place to life. dean reynolds, cbs news, chicago. when we come back, a dangerous mission of mercy at the south pole.

tonight a daring rescue attempt is ongoing at the bottom of the world. a small plane flew nine hours, 1500 miles to a science station at the south pole. a sick worker there needs to be evacuated. but winter has just begun. it is 74 below zero and dark. the dejavelin twin otters, similar to this one, one of the few planes that can operate in that weather. the crew hopes to fly out tomorrow. coming soon to your smart phone, 72 new emojis, approved by the agency that regulates such things. among them, the rolling on the floor laughing emoji, all kind of animals, and vegetables, a dancer who looks to us a lot like john travolta, a pregnant woman, and if you have had enough, the raised hand emoji. we really like them.

and we'll be right back.

finally tonight, investigators have closed the case of three civil rights workers who were murdered in mississippi. correspondent bill plante covered the crime for cbs news more than half a century ago. ♪ ♪ >> reporter: they called it freedom summer, 1964. a drive to register blacks long denied the right to vote. at a rally, andrew goodman heard what would become his fate. awe they should expect to spend it in jail, they should expect possibly somebody to get killed. >> reporter: then 52 years ago tonight, goodman, james earl chaney were murdered taken by the ku klux klan, with the help of a sheriff's deputy shot at

point-blank range and buried. their disappearance shocked the nation and captured the eye of norman rockwell who created this haunting image for "look" magazine. i was one of the swarm of reporters sent to mississippi. in chicago where i grew up racism was easier to ignore. in philadelphia, mississippi, it was up close and personal. we were outsiders, met with hostility. president johnson sent the fbi and was briefed regularly by director j. edgar hoover. apparently what's happened these men have been killed. well now what would make you think they have been killed? >> because of the fact that it is the same car that weer in philadelphia, mississippi. >> reporter: the bodies of the three men would be found together, six weeks later. the williams, chaney, goodman, and schwerner joined emmett till to jimmy lee jackson whose

deaths would be gated after a federal law in 2006. 41 years after the civil rights workers were killed the state of mississippi won a manslaughter conviction against one more of the klansmen. it would be the last conviction. most of those who knew anything have died. the case that became known as mississippi burning is now officially closed. but there is something else. in goodman's last words to his parents, found on a postcard, all my love, words that heal. bill plante, cbs news, washington. >> that's the "overnight news" for this wednesday. for some of you the news continues. for others check back a little bit later for "the morning news" and of course, "cbs this morning." from the broadcast center in new york city, i'm scott pelley.

this is the "cbs overnight news." >> welcome to the overnight news. i'm done dahler. great britain and europe bracing for tomorrow's vote that could change the face of the continent. the brit is are holding a referendum on whether or not to remain in the european union. the brexit as the it is called split families and divided the nation. polls show older, working class voters in england generally favor leaving. younger, belttter educated vote want to statement. it divided the political establishment, david cameron favors remaining in the eu. former mayor, boris johnston wants out. >> i know europe isn't perfect, believe me, i understand and i see those frustrations.

i feel them myself. that's why we negotiated and enhanced our special status. out of the euro, keeping our borders, not involved in ever-closer union, we have the best of both worlds. as you take this decision, whether to remain or leave, do think about the hopes and dreams of your children and grandchildren. they know their chances to work to travel to build a sort of open and successful society they want to live in rests on this outcome. >> i wanted, the last thing i wanted was to go against -- david cameron or the government. but after a great deal of heartache, i don't think there is anything else i can do. i will be advocating, that leave, whatever the team is called, i understand there are many of them. that is, that is basically, because i want a better deal for the people of this country.

>> reporter: last week, a british legislator was killed while campaigning to remain in the eu. >> here in the u.s., a british man is being held without bail after telling the secret service he was trying to kill donald trump. michael steven sandford tried to grab an officer gun in las vegas he later told investigators he had been planning the assassination for a year. >> reporter: investigators say the suspect had been training at a las vegas gun range in the hours before he was arrested. authorities say he fired 20 rounds at a target from a 9 millimeter glock pistol before putting his plot into motion a day later. >> i love las vegas! >> reporter: the gop presumptive nominee did not know what was really happening in the crowd at this campaign stop in las vegas. according to investigators, what appeared to be a disturbance was actually 20-year-old michael steven sandford's disrupted plot

to kill donald trump inside treasure island casinos theet ter. he was quickly rushed away. >> thank you. thank you officers. >> reporter: according to court documents. sandford got up from his seat and approached an officer saying that he was seeking an autograph from trump. he then attempted to take the officer's weapon. by grabbing the holster and handle with both hand. investigators say he admitted to trying to shoot and kill trump acknowledging he would likely only be able to fire one to two rounds before being killed by police. this isn't the first threat to trump on the campaign trail. >> in march, a demonstrator was arrested in a rally in dayton, ohio after he tried to rush the candidate on stage. in recent months the candidate's west coast campaign stops have on occasion included violent encounters between protesters, trump supporters, and police. trump hasn't been the only target. >> step away. right there. right there. last month secret service agents

jumped into action to protect bernie sanders when at least five people stormed the stage at a campaign stop in oakland. >> we don't get in tim dated easily. >> reporter: there is security camera footage of the incident in las vegas. but it is not yet been made public. according to a public defender, sandford who is a british citizen was here in the u.s. illegally with an expired passport. he will be in court again early next month. >> moon while trump has political problems as well. he fired his long time campaign manager. and has been having a difficult time raising money for the fall campaign. chip reid has that. >> cory lewandowski may have led donald trump to a record breaking primary victory. monday the calls for his ouster appeared to sing in. trump had his former top aid escorted out of trump tower. trump said the beginning of a different kind of campaign. >> he is a good man. we have had great success. >> reporter: last night, donald trump praised controversial former campaign manager cory

lewandowski. the decision to fire him trump said was a strategic shift. >> i'm really proved him. he did a great job. we are going to go a little different route. from this point forward. >> a different style. and you are bringing in. >> little different style. >> during his long year campaign. trump was repeatedly forced to defend his former aide. >> cory, good job, cory. >> reporter: even boasting about his loyalty when lewandowski was accused of grabbing and bruising a female reporter. >> it would be very easy for me to discard people. i don't discard people. i stay with people. >> reporter: lewandowski clashed with colleagues and trump's own children. ultimately his daughter. ivanka was a major influence. the party chairman said promoting veteran operative, paul manifort signaled a pivot to a serious general election campaign. >> there is no way to work a campaign with competing factions and competing understandings of what the right approach will be.

>> reporter: one area lewandowski was seen in lacking was general election fund-raising. according to new numbers filed monday. trump's campaign and supporting committees had over $21 million on hand end of may compared with more than $100 million for team clinton. >> the mayor of oakland, california, insists heads will roll at the police department. the department has gone through police chiefs in a week. right now, it's under civilian control. >> reporter: we are hell bent on rooting out this disgusting culture. in no uncertain terms, oakland's mayor is vowing to get to the bottom of the sex scandal rocking the city police force. >> i feel this is an appropriate time to place civilian overnight over this police department. >> reporter: the department's high stakes game of musical chairs started june 9th when sean whent resigned.

ben fairow removed six days later because of still undisclosed information that led the may your to lose confidence in him. assistant chief, paul figueroa took over to resign two days later. things began to unravel in september after an officer killed himself and left a suicide note claiming several officers were having sex with a teenage prostitute. >> the first one at 16. >> the young woman at the heart of the scandal goes by the name, celeste, is cooperating with investigators. she told our station, kpix, that looking back she believes officers took advantage of her. >> at the time, no, i was happy to, wow, you know, these men in uniform, giving me protection. but, now that i am 1, looking back at it, yeah, i do feel, i do feel like they did. >> reporter: at least 14 officers are involved in the sex scandal. two have resigned. to find out that my own police

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china is apparently making good on its pledge to stop supporting hackers, targeting american companies. fire eye, the online security company known for fighting sophisticated chinese hack attacks says security breaches linked to china-based groups are down 90% over the past two years. the justice department kids chinese espionage a national security emergency. there are more investigations and more prosecutions, but the dragnet sometimes snares the innocent. bill whitaker reports for "60 minutes." >> it was so urgent, pounding so urgent that i run here to open the door without being fully dressed. >> reporter: last may the fbi paid an early morning visit to scientist xia xing xi to his

home in suburban philadelphia. >> i open the door. i see a lot of people outside. >> bulletproof >> yes and guns. >> xi is chair of the temple physics department. convince heed was a spy passing high tech secrets to china. he was stunned when agents burst in and handcuffed him. >> reporter: did you have any idea what was going on, why they were here? >> no, i had absolutely no idea. so the very first thing i went through my mind was -- this must be a mistake. >> reporter: xi couldn't believe this was happening to him in the u.s. he was born in china and raised during the cultural revolution. a time when families feared an unexpected knock on the door. his father, a lawyer, was taken away to a forced labor camp. as an adult, xi came to the u.s. to live and work in a free

country. why did you become an american citizen? >> my children were born in this country. my home is in this country. my career is in this country. so it is just feel natural that i become a citizen. >> reporter: xi established himself as a world leader in the study of superconductors that could help improve mris. he managed nine government research projects and more than $1 million in federal funding. >> this is your lab? >> yes. >> one of your labs? >> one. yes. >> reporter: the arrest had a swift impact. temple told him to stay home. he was removed as the principal investigator of his own research. what's going through your mind? >> so i was saying to myself, they're going to put me in jail. and all of these things that i have been working for years was coming to an end. >> reporter: tell me about the day you were arrested?

>> my life was turned upside down. >> reporter: sherri chen's life was turned upside down when investigators suspected her of spying for china. she has been a u.s. citizen for 19 years and devoted her career to public service as flood forecaster in the state of missouri and with the national weather service in ohio. >> reporter: you were proud of your work? >> yeah, i do. i really poured my heart into my work. >> reporter: chen showed us the award she won for helping to save the city of cairo, illinois, for record flooding in 2011. armed with her forecast, the army corps of engineers blew up a levee and rerouted floodwaters. what did you feel about that when cairo was spared? >> i am proud of that. my knowledge, my work really protected the properties and the saving peoples lives. >> reporter: three years later,

chen says, fbi agents marched her out of her office in handcuffs. >> i saw my co-workers all looking through the windows. and they watched me being taken away. >> i think prosecutors are feeling pressure to bring these cases. i think investigators are excited about bringing cases that may be high profile. >> reporter: attorney peter zeidenberg, a former federal prosecutor who represents xi and chen. he believes both american citizens are collateral damage in the government's war against chinese economic espionage. that fear of chinese economic espionage it is not unfounded? >> no, i am not suggesting that it is. what i am suggesting is notwithstanding that fact, before you put handcuffs on some one and take them away, that you got to make sure that you have got your case together.

and that the facts add up. >> reporter: in these cases -- >> facts didn't add up. >> reporter: xi faced a justice department narrative worthy of a spy thriller. prosecutors accused hem of collaborating with various government entities in china, of scheming for years to obtain revolutionary american technology, and e-mailing photos and blue prints of the technology to the chinese. specifically, this american-made device called a pocket heater. it is used to make a super fine coating that maximizes the flow of electricity. in exchange, prosecutors said he would be showered with money, property, and prestige in china. >> the very first word coming out of my mouth was -- that's absurd. that is really absurd. >> why? >> reporter: it turns out the device xi was discussing with his chinese academic counterparts wasn't a pocket

heater. it was a completely different heating device that xi was developing. he planned to share it in scientific publications. it was an earlier generation of this one. is this in any way similar to the pocket heater we have been talking about? >> not at all. it is very different from the pocket heater. >> reporter: so when it kmz to the science, sounds like the federal investigators flat out got it wrong? >> that's correct. >> reporter: and then there is this. prosecutors allege that xi's collaboration with chinese scientists was some how sinister. in reality it was mandated by one of his grants from the national science foundation. so your funding was dependent on your working with schien ease scientists. >> yes, yes, yes. absolutely. >> one arm of the government wants you to collaborate, the other arm of the government says it is a crime. >> indeed. indeed, yes. >> reporter: yet he faced #le 0 years in prison. >> what was that like? >> it put a lot of stress and --

and this stress, sometimes becomes strikingly unbearable. so -- i remember pleading with my family, let's -- let's -- try not to fold. if we hold on -- we know the truth. if we fold, we will have nothing. >> four months after she is a rests, her lawyer pointed out inconsistencies to the attorney general's office in philadelphia. three weeks later they dropped the case. and he sees disturbing parallels with sherri chen's case. how did she get into trouble? >> the story started when she went to china to visit her

parent. she had a some what happenstance meeting with a former class mate of hers, vice minister in water ministry. >> reporter: the vice minister asked chen how the u.s. pays for dam repairs? >> did you think there was anything, i don't know, secretive about that information. >> it never crossed my mind. i, it's not a secret. >> reporter: when chen got back to ohio, she asked her boss for publicly available information which she did send to her former classmate. she also searched this government database. since she wasn't a regular user, chen borrowed a password from her colleague. sharing password was comb moin in the office. she never sent information from the database to china. but federal prosecutors charged chen with illegally accessing and stealing restricted information. prosecutors also charged her with lying about the password. chen initially denied that a

colleague had e-mailed it to her. but she remembered after investigators showed her the e-mail. her colleague, ray davis initially forgot too. >> he wasn't charged with misremembering for failing to remember to give her the password. he remembered when they showed him the e-mail. literally, that was almost a year ago. i forgot about that. >> wasn't that sherri's reaction? >> it was. >> why the dispretty reactions from the government? >> the fact is that sherri chen is a chinese-american. and her colleague was caucasian. with sherri everything she did they looked at, as some how nefarious, or some how why are you deleting these photos? because my teeth are yellow. why don,t you use a whitening toothpaste? i'm afraid it,s bad for my teeth. try crest 3d white. crest 3d white diamond strong toothpaste and rinse... ...gently whiten... ...and fortify weak spots. use together for 2 times stronger enamel.

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just click it in and recycle! to enjoy continuous clean freshness with every flush for up to one week. lysol click gel keeps it clean with one click. lysol. start healthing. the olympic games in rio less than seven weeks away. but there are also olympic-sighed problems. from construction delays to political unrest to the zika virus. ben tracy is there. >> reporter: that's the sound of rio racing to be ready. the president of the international olympic committee came to check on city's progress and unveiled the rio olympics medals. >> brazil need now the most something which is unifying the country because we see from

outside we see deep divisions. >> reporter: this is rio's olympic park where most events will take place. almost all of the venues down there are now complete. all over the city they're still rushing to got a lot of work done. giant stands for spectators to watch volleyball are going up on copacabana beach. new highway to the olympic park just opened. but a new $2.8 mass transit extension is very much unfinished. we went underground to see rio's delayed subway project which is transporting as many as 300,000 people every day. this is the inside of one of the stops on the subway extension here in rio that will take tourists and athletes to olympic park. you can see ticket takers are ready to go. there is still plenty of construction being done here. this is not scheduled to be finished until four days before the games begin. but the olympic spirit is not

being felt in rio's poor areas. the favelas that sprawl over the city's hill sides. >> you have lived here since you were a baby. >> felipe says the $11 billion spent on the games won't make his life better or safer. >> it is commercial for, for the foreigners, for the investors. >> reporter: are you excited the olympics are here? >> no. >> reporter: no? why? >> the investment is not for us. it is for the foreigners. >> reporter: we wanted to ask rio's mayor about the criticism and the still horribly polluted waters many athletes will be competing in. he canceled an interview with us twice on the same day a major media outlet accused him of corruption. he is not alone, the brazil scandal plagued president could be formally removed from office just days before the games begin. yet brazil's interim president says the world won't care about the political crisis once the

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there is a dangerous rescue operation under way at the bottom of the world. two planes arrived to evacuate a sick contractor. >> reporter: flying to the south pa pole is difficult, the continent is in the middle of the pitch-dark winter as it is now, weather conditions make flying practically impossible. with a sick contractor in need of evacuation and the clock ticking there is little choice. two twin otter planes dispatched from canada will attempt the midwinter rescue. done just twice before. in 2001 and 2003, sean lutig flu on both missions. >> we face similar conditions to what the guys will face this week. cold temperatures and no light whatsoever down -- at the south

pole. >> reporter: on monday the planes landed at britain's station on the antarctica peninsula. weather permitting one aircraft will make the roughly 1500 mile flight to the south pole. the second will stay behind in case the first runs into trouble. >> the big consrn cern you don' have enough fuel to go to the south pole turn around and come back. the contractor's name and condition have not been released. a second patient may need to be evacuated. temperatures outside are hovering at minus 60 degrees fahrenheit. while the rescue planes can with stand the extreme cold and use skis to land on the ice, in prior rescue missions, flaps and other vital systems have frozen over. >> so the skis heat up. when the plane stops, it froze to the, to the ice, which, we weren't expecting. so when it came time to leave. we were stuck. couldn't get the plane loose. >> the doctor use evacuated in

2001 because of a gall bladder infection. david panzera of air national guard has flown to the south pole more than 300 times. >> go from blue skies look you see behind me today with light cloud in the air to a total whiteout. very, very, unsafe, and, very, very strange place. panzera's unit evacuated dr. gerri neilson who treat herd self for breast cancer in 1999. she had to wait until end of didn't tire leave. something current rescuers hope to avoid. >> the challenge is always ghg to be the temperature and the weather. those two most uncontrollable factors whether it is our airplane or theirs. >> that's the "cbs overnight news" for this wednesday. for some of you the news continues. for others, check back with us a little later for the morning news and cbs this morning. from the broadcast center in new york city, i'm don dahler.

captioning funded by cbs it's wednesday, june 22nd, 2016. this is the "cbs morning news." >> just like he shouldn't have his finger on the button, he shouldn't have his hands on our economy. [ applause ] >> in a scathing speech, hillary clinton goes after donald trump's economic policy using his own words and finances against him. trump didn't hold back when it came to firing back. >> basically she's crooked hillary. i mean, when you get right down to it. we're getting a glimpse into the life of the gunman w