Hours after mocking, ridiculing and challenging donald trump on the debate stage, a rejuvenated marco rubio struck again today. Then donald trump struck back with a surprise announcement of new jersey governor Chris Christie. It was all part of a nasty back and forth war of words between trump and rubio on the trail just four days before super tuesday. Nbcs katy tur starts off our coverage. Katy, what a day. Reporter lester, they say everything is bigger in texas, and this endorsement certainly came as a big surprise. Less than a month after he dropped out and just four days to go until super tuesday, Chris Christie is getting behind donald trump and trying to lay waste to marco rubio. Ladies and gentlemen, it is my honor and my privilege to introduce the next president of the United States, donald trump. Reporter donald trump added a little jersey pride to his texas swagger in fort worth today. Former president ial candidate chris frontrunner. I really was happy with this one right here. Chris, thank you. We love you, man. Its all make believe. Reporter less than a month ago, christie was trying to tear down trump. I never said that i could shoot somebody in the middle of fifth avenue and i wouldnt lose a voter. I never calls mexicans rapists and murderers. I never said ban all muslims from the United States. Reporter the new jersey governor and new york mogul both often called bullies, now teaming up to eviscerate marco rubio. You know, last night i thought the deal of the night was when i looked over to rubio, and i said, you remember, youre a choker, and we dont want chokers in our administration. I said, youre a choker, and youre a liar. Reporter trump again mocking rubios state of the union water bottle gaffe. Lets talk about our lightweight senator from florida. He doesnt have the talent. He can never make us great. Reporter the endorsement, Perfect Timing for trump after a bad debate that let for his inheritance. A Trump University fraud suit and not releasing his tax returns. The irs has said theres nothing precluding you in its rules from releasing your tax returns with an audit. Until my audit is finished, very simple. Youre not going to see anything. When its finished, youre going to see it. But im not going to complicate things. Reporter christie, a cunning application whoment believed could have bridged gaps in washington, is picking the sure bet. Sources familiar with the governors news. But rubio, after standing up to trump at the debate, isnt going to go down without a fight. Katy tur, nbc news, fort worth, texas. Reporter this is Gabe Gutierrez covering marco rubios campaign. Today he was riding high until the billionaire dropped the bombshell. How stunning was the christie endorsement . Stunning . No, i mean, look, guy. Donald probably needs night. Christie. I respect that. Reporter this morning in dallas, rubio had ripped into the frontrunner. What we are dealing with here, my friends, is a con artist. Reporter mocking a series of trumps misspelled tweets. And i only reached two conclusions. Number one, thats how they spell those words at the Wharton School of business where he went, or, number two, just like trump tower, he must have hired a Foreign Worker to do his own tweets. He called me mr. Meltdown. Let me tell you something. Last night in the debate during one of the breaks two of backstage. He was having a meltdown. First he had this little makeup thing around his mustache because he had one of those sweat mustaches. Then he wanted a full length mirror. Maybe to make sure his pants werent wet. Reporter rubios all out of salt coming out of last nights debate in houston. He berated trump for his hiring practices. If he hadnt inherited 200 million, you know where he would be reporter and his slogans. Now hes repeating himself. No, no, no. I watched him repeat himself five times four weeks ago. I watched you repeat yourself five times five seconds ago. Reporter rubio faces a steep climb. Polls show the senator behind trump in all 11 states. Whats crucial is rubios home state of florida on march 15th, where one poll has him trailing by double digits. Youre guaranteeing that you will win . What happens if you dont . Well win florida. Reporter as rubio campaigns throughout the south tomorrow, hes expected to release his own tax returns, and hes calling on the gop frontrunner to do the same. But, lester, on a day when rubio woke up owning the news cycle, he found himself trumped. Gabe, regarding some of those allegations by rubio, coming up, weve got the inside story of how undocumented workers worked at the site of trump tower. Bring in our political director, the moderator of meet the press, chuck todd. Chuck, our new poll asked registered voters which of the following would be their reaction to trump as the nominee. 51 said scared. 24 said angry. When you look at numbers like that and you look at that back and forth we just saw a moment ago, what do you make of it . I have to say it feels like every time we think Public Discourse has deteriorated to a new low, we reach a new low. It really is stunning the back and forth today that weve seen between trump and rubio. It is unpresident ial doesnt even begin to describe it. But, look, the fact of the matter is youve got to give the Trump Campaign credit here. This christie endorsement, timing and symbolism are big with endorsements. A lot of times theyre overrated, but the timing of it was brilliant. You have to say that. It shows you this is a very Sophisticated Campaign that trump has. He had this in his bag of tricks ready to go when he needed it. Chris christie is a card carrying member of the republican five stages of grief going on, lester, the fifth stage is acceptance with republicans. Christie is a big acceptor. Republicans soaking up the headlines today but lest we forget, democratat and voters in South Carolina primary tomorrow. What are we looking for there . Well, it should be a big win for hillary clinton. If its not, it shows you that there is life in sanders campaign. Sanders needs to improve with africanamerican voters, and if he does that, well know because hell come within Single Digits of her. But if its a double digit win for her, it could be foreshadowing of a long night for Bernie Sanders on super tuesday. Thank you. Shock and horror in another American City tonight. The scene of this countrys latest mass shooting. This time, four dead including the shooter and 14 wounds after that gunman went on a rampage at multiple scenes. Most of the carnage inside his place of work. Miguel almaguer has new developments in the investigation. Reporter a gunmans facebook page. Police say cedric ford used an Assault Rifle to hunt and kill his victims. Close to 5 00 p. M. Thursday, two shootings at two intersections. Two people are wounded before ford speeds away. He then arrives at work, excel industries. Detectives say ford opens fire on a coworker in this parking lot, then enters the building. All of a sudden, pop, pop, pop, pop. Reporter ford fires on everyone in sight. He was following people out the back, and i thought he was going to shoot me. Reporter 14 are wounded. Three killed. 24 minutes of terror only coming to an end when a Police Officer storms the building, taking fire as he enters. The only reason he stopped shooting is because that officer stopped the shooter. Reporter cedric ford had a 20year criminal history. A felon charged with burglary, grand theft, and carrying a concealed weapon. In court documents, his exgirlfriend asking for a protective order, alcoholic, violent, depressed. Its my belief hes in desperate need of medical and psychological help. Police served that restraining order to ford at excel shortly before the shooting. Dennis britton jr. , shot once, thought about his three children as he was rushed to the hospital. I didnt want to leave them. I wasnt ready to leave yet. I didnt want to die. Reporter tonight, heartbreak in this Small Community for the dead. Renee benjamin was 30. Brian sadowski, 44, loved rock music. Joshua higbee, 31, a young father who loved his little boy. He didnt deserve this. Reporter tonight, several people remain hospitalized, including one in critical condition. Police say ford was armed with an Assault Rifle and a handgun. Nbc news has learned those weapons were bought by an exgirlfriend, though not the same girlfriend who filed that restraining order. Lester, we are told 200 to 300 people were had that Police Officer not engaged the suspect quickly, the death toll could have been so much higher. Lester. Miguel almaguer tonight, thank you. For the first time, the cdc is recommending that pregnant women not attend the summer olympics in brazil. Ground zero for the zika virus, which is linked to birth defects. There are now more than 100 cases in this country, and as our rehema ellis explains, several pregnant women in the u. S. Have contracted it. Reporter for weeks, the centers for Disease Control had been on the lookout for pregnant women returning to the United States from countries where zika has been linked to microcephaly. Today, the cdc confirmed nine pregnant american women with zika, and is investigating another possible ten. We described women who developed zika after traveling, got it from a place where zika is spreading, and then are currently pregnant or delivered a child. Reporter two pregnancies ended in abortion. Of the three babies severe birth defect. Nationwide, the number of zika cases is growing. There are now 24 states and washington, d. C. With confirmed zika virus. At least 107 cases so far, all involving people who had traveled abroad. And now doctors at Seattle Childrens Research Institute in washington are sounding the alarm that the birth defect linked to zika could be even more devastating than originally feared. In brain scans comparing microcephaly cases, doctors found a babys brain with zika was so severely damaged, it was almost gone. Suddenly seeing something this severe and this new in such numbers is unprecedented. Ive never seen the like in my career. Reporter tonight, Health Officials are warning there could be thousands of zika cases in puerto rico this summer, and the race is on to distribute mosquito protection kits there. Rehema ellis, nbc news, new york. Still ahead tonight, millions saw in last nights debate of exploiting undocumented workers at the site of his trump tower. What really happened . Tonight, the results of an nbc news investigation into that. Also youre not just seeing things. Thats a unicorn, sort of. And she led police on a wild chase thats now the stuff of legend. One. Now to that controversy that has roared back into the headlines about donald trump and one of the most Famous Properties that bears his name, trump, who vows to deport all undocumented immigrants, was accused in last nights debate of using undocumented labor himself at the site of trump tower. Nbc news has investigated what went on there for months now, and tonight nbc news Senior Investigative correspondent Cynthia Mcfadden reveals what we found. Reporter last night, marco rubio let loose on donald trump. You lied about the polish workers. Yeah, yeah, yeah. He lied 38 years ago. I guess theres a statute of limitations on lies. Reporter in the 1980s, undocumented immigrants did do much of the initial work on the crown jewel of his empire in new york, trump tower. Which raises the question, is donald trump a hypocrite . Is it accurate to say that trump tower, the construction of it began on the backs of polish workers who were unpaid . Oh, absolutely. Its constructed on the blood, sweat, and tears of the polish known in the industry. Reporter back then, attorney wendy sloan sued donald trump, his company, and others, claiming they failed to acknowledge at least 150 undocumented polish men working off the books. Donald trump testified and was asked what working off the books in the construction meant. His response, i really dont know. They had know protective equipment, no helmets, hard hats. In his testimony, ep denied he knew the workers were illegal. Did it ever come to your attention that any of those polish workers were illegal aliens . I really still dont know that. Nobody has proven to me that they were illegal aliens. It seems he was saying, in essence, that everybody else in town knew what was going on on his own job site, a a he didnt. Reporter daniel sullivan, a Labor Relations consultant who had been convicted of tax evasion, testified that during the demolition, trump himself knew he was using illegal workers theres no question in my mind. I mean he said it to me point black. Reporter nbc spoke with sullivan in 1989. He has since died. Donalds lying. Flat out. He knew exactly what was happening. Reporter one of those workers says he was promised 5 an hour but wasnt paid for all of his work. You must have been angry . Very angry about that. Reporter he was one of only a few polish workers with a green card. Several undocumented workers testified at the time they were making only 4 an hour while the American Union workers were making 12 to 14. They also said they were not paid for months of work. But at the time, were too afraid to protest outside the building. Theyre looking for not legal people so that people are very afraid of all that. Reporter mr. Trump told us it was the contractors responsibility to pay the demolition workers, not his. Agreed. Still, he never reported the workers or tried to get them deported. Mr. Trump also told us he would have done nothing different. And, again, last night defended himself. Ive hired tens of thousands of people over my lifetime. Be quiet. Let me talk. Ive hired tens of thousands of people. He brings up something from 30 years ago. It worked out very well. Everybody was happy. By the way, the laws were totally different. That was a whole different world. Reporter despite rubios claims, what trump ultimately paid to settle the matter was sealed by the court. Nonetheless, in the final ruling on yet another case involving the polish workers and trump tower, the u. S. Court of appeals wrote that in the end, time generally reveals what a falsehood hopes to hide. But when it comes to mr. Trumps appeal among voters, consider this. One of the polish workers who didnt get thought donald trump might be a very good president and was considering voting for him. Lester . Cynthia mcfadden tonight, thank you. Were back in a moment with that irs hack far worse than we were first told. How youll be able to stolen. Disturbing news from the irs today revealing that a cyberattack may have affected far more people than first reported. In all, 700,000 households may have had their information stolen. Experts say we could see a surge in fraudulent tax returns. The irs says it will notify the affected taxpayers in the coming days. A hollywood passing to note tonight. Tony burton, who was best known for playing apollo creeds trainer in the rocky movies has died. Burton was a successful prize fighter of his own as a young man before moving into acting, aer paing in six rocky films in all. The 88th Academy Awards are this sunday and its one of the most dpev in recent history. Many are betting Leonardo Dicaprio will take home his first best actor oscar, and brie larson is the best actress favorite for room. But overshadowing all this controversy, some like spike lee and will smith are boycotting the ceremony over the lack of nominees of color in the acting categories. When we come back here tonight, a wild unicorn chase . The great escape that had witnesses wondering what exactly seeing . Finally tonight, whether you knew it or not, its National Tell a fairy tale day, and do we ever have the right story for the occasion. Its about a beloved pet that got loose and had something thinking maybe for a split second are unicorns real. Nbcs joe fryer has our tale. Reporter one can only imagine what drives in Rural California were thinking when this galloped into sight. The calls were coming in as a unicorn running around out there on the roadway. Reporter it time in madera ranchos, california, where this horned creature led police on a threehour chase. Avenue 12. The owner is trying to corral her. Reporter turns out the unicorn was a phony. In real life, shes a pony. Her name is juliette, and she belongs to 5yearold tay item. I love my pony. Reporter juliette wears the horn to pose for professional pictures with children. But she made a run for the rainbow. She got afraid, and then she runned away. Reporter she dashed through orchards and darted in and out of traffic. She turned out to be stealthier than we would have imagined. Reporter a situation reminiscecommend. She was eventually wrangled by a neighbor with a horse that lured her out of hiding. The call came out that the unicorn was in custody. As tense as the situation was, that was the comedic relief needed at the time. Youll yet escaped the wrath of the law. Tatum was no so generous. She got a timeout because she was being a bad pony. Reporter her horn is now gone, replaced with two other horns, but at least everyone in this fairy tale lived happily ever after. Joe fryer, nbc news. And that will leave us with a smile on our face on this friday night. Im lester holt reporting from los angeles. For all of us at nbc news, thank you for watching and good night. It has been a trial five years in the making for cody wallace. What todays verdict was that could surprise you. Plus. I walked down the snack aisle of a Grocery Store and looked at all the labels. And, this adorable puppy needs your help in getting a second chance. How you can help the puppy with a rare condition. We have a storm offshore. But it wont affect our changes too much. We will discuss them next. News 4 nightly starts now. You are watching news 4 nightly on your side in high definition. Good evening, a verdict is in. A jury has found cody wallace not guilty of first degree murder charges however he was found guilty of child neglect. He had been arrested and charged with the death of Thomas Odonnell in 2010. He has been in jail since his arrest. The victim was the son of his afternoon and this morning before reaching the verdict. His Attorney Says he never should have been charged with murder in the first place. We believe had tabitha decided to go to the hospital, that this little boy would still be alive. Sentencing on the child neglect charge is set for next month. Wallace could get two to 20 years on that charge, but he will also get credit for time served. That is the past five years he spent many the county jail waiting for trial. In other news tonight, a shooting killed one reno teen and injured two others including an officer last night. Sparks police say four men carjacked a vehicle in sparks and were later spotted at casino in silver springs. A deputy approached the car and someone inside opened fire hitting the deputy in the hand