Announcer from nbc news World Headquarters in new york, this is nbc nightly news with lester holt. Good evening. It is like nothing weve seen before in modern american political history. Mitt romney, the republicans last president ial nominee, delivering a stinging pointbypoint takedown of his partys current frontrunner, donald trump. The stop Trump Movement reaching a new level of urgency with romney, in a speech that at times sounded like an intervention, labeling trump a phony, eviscerating his policies as reckless, and accurately predicting trump would launch a counterassault. Its clear were witnessing open warfare tonight over the future of the Republican Party, and we have two reports starting with nbcs peter alexander. Reporter in under 20 minutes, romney branded his partys frontrunner as dishonest, dangerous, and dumb. Heres what i know. Donald trump is a phony, a fraud. His promises are as worthless as a degree from trump university. Reporter the dean of the Republican Party and his last vilifies the man best positioned to succeed him. You say, wait, wait, wait. Isnt he a huge Business Success . Doesnt he know what hes talking about . No, he isnt, and no he doesnt. His bankruptcies have crushed small businesses, and the men and women who worked for them. He inherited his business. He didnt create it. And whatever happened to Trump Airlines . And then theres trump magazine and trump vodka and trump steaks and trump mortgage. A business genius, he is not. Reporter repeatedly blasting the billionaire for lacking the temperament to be president. Think of Donald Trumps personal qualities, the bullying, the greed, the showing off, the misogyny, the absurd thirdgrade theatrics. Reporter and accusing trump of manipulating the publics anger. He creates scapegoats of muslims and mexican immigrants. Reporter four years ago, romney welcomed trumps endorse. Thank you, donald. Today tweeting if trump had made his controversial comments then, he wouldnt have accepted it. But if not trump, then who . Id vote for marco rubio in florida and john cass meteoric in ohio, and for ted cruz. Could romney jump in. If its trump, this dire prediction. A person so untrustworthy and dishonest as Hillary Clinton must not become president. Of course, a trump nomination enables her victory. Reporter peter alexander, nbc news, salt lake city. Reporter im katy tur. Mitt romney predicted it. Will he talk about our policy differences or will attack me with ifn sult . Reporter did and donald trump delivered. I could have said, mitt, drop to your knees. He would have dropped to his knees. He was begging. Reporter the gop frontrunner is back at the namecalling today. Hes a choke artist. Reporter a sentiment about romney echoed by trumps supporters. Who is he . Hes a loser. Reporter the former nominee now daring the potential nominee to be transparent. All he has to do is release his back taxes like he promised he would. Reporter demands trump ignored. The gop frontrunner taking fire offstage is about to face it onstage. Tonight his toughest rematch yet. Head to head with fox news moderator megyn kelly for the first time in eight months. The billionaire trashing kelly after she asked him about his own words, insulting women. Youve called women you dont like fat pigs, dogs, blobs, and disgusting animals. Only rosie odonnell. Reporter tonight, sure to get heated with no ben carson, only four podiums are left. Swha your plan . Aides to marco rubio promising the senator will expose the billionaire for his policy shortcomings and will get personal if he needs to. Trump now on the air in rubios home state, spending 1 million on florida tv. Meanwhile the Cruz Campaign down less than 100 delegates, says the texan wont get in the mud. Either way, trump says hes ready. They said act president ial tonight. I said ill act president ial, but if somebody hits me, im going to hit them back harder e. Reporter meanwhile john kasichs camp says hes going to try and stay out of the fray tonight, but make no mistake. Donald trump has the most to lose. He may be in the lead, but not by much, lester. Katy tur, thank you. We want to bring in our political director, the moderator of meet the press, chuck todd. What just happened here and whats the end game, chuck . I can tell you this. The other republican campaigns who want to stop trump are a little bit disappointed that mitt romney didnt offer a solution, and they fear that mitt romneys solution to all this is him raising his hand, saying, hey, im available in case of emergency. Well, how could that work out . Donald trumps rivals have 12 days to stop him. Trump has not put this nomination away. In fact, if trump loses both florida and ohio, chances are were headed to that contested convention. Trump leads in the delegate and as katy said, less than 100. So far trump has won about 40 of all the delegates available. Lets assu hes really got to do well in florida and ohio. Let me explain. If trump wins both florida and ohio, this is what his delegate total will look like. Hell have nearly a 300 delegate lead over cruz. Hes need to only win 50 of remaining delegates to be the nominee. Guess what . Without rubio and without kasich, both would drop out, that wouldnt be the case. But if he loses both florida and ohio to kasich and rubio, then suddenly you have a jumbled mess. Everybody stays in, and, lester, were headed for that contested convention. Chuck, thank you. We want you to know mitt romney will speak out live tomorrow morning in studio here in new york. An exclusive interview with matt lauer on today. Meantime, you think Hillary Clinton might be sitting back today gleefully watching whats happening on the gop side, but she has got potential trouble of her own, namely this email controversy that repeatedly surfaces. This time word that the aide who set up her private email server has been granted immunity. Nbcs Andrea Mitchell now with new details. Thank you all so much. Reporter Hillary Clinton at a star studded fundraiser last night. At the same time as a new disclosure about the investigation into her emails. Nbc news confirming the former aide who set up her personal server has been granted immunity by the zwrush department. Brian pag lan know had taken the 5th before congress but now is talking to the fbi. Spotlighting an issue donald trump raised again today. Assuming shes not arrested for the email situation. Reporter key legal issues, with classify information miss handled, what was the damage . What was her role . The overriding legal issue is what was done at her direction and what was done with her knowledge . Reporter the fbi director has taken charge. I am very close personally to that investigation. Reporter today clintons spokesman said she is eager to be interviewed by the fbi. Calling secretary clinton in to answer some questions may be one of the final steps to help them wrapping up the investigation. There is no classified materials. Reporter its a controversy that has now shadowed clinton for a full year. Did you wipe the server . Like with a cloth or something . Does it raise judgment questions . I dont think so. Reporter Bernie Sanders gave her a pass on the issue last fall, and today his wife and adviser told me maybe more people are interested now, but were not going to make an issue out of it. Reporter it is very likely that clinton will have to testify. Her team says theyre glad her former aide is now cooperating, but clearly no matter what the Justice Department decides, this is an issue the republicans will continue to use against her. Lester. Andrea, thank you. There were new developments tonight involving that piece of debris discovered off eastern africa, possibly belonging to the missing Malaysia Airlines flight 370. Malaysian authorities reiterated today that photograph meteoric evidence suggests it likely came from a boeing 777. Were hearing more from the american who found it. Heres nbcs tom costello. Reporter the photographs of the possible debris found off mozambique raise several questions. Why is there no marine life like we saw on the first piece of debris that washed ashore last summer, covered in barnacles on nearby reunion island . Oceanographers say it is possible it could be washed clean in it was stuck in the sand. Yet the words no step are still visible. Does the rip pattern on the debris shed any light . Experts say it suggests a violent impact with the water, but theyd expect to see a relatively flimsy stabilizer rip off first. I cant confirm at all thats a piece of a plane or a piece of anything to do with mh370. The piece was found off the coast of mozambique by blaine alan gibson. This could possibly be from malaysia 370. We dont know yet. Gibson has blogged about mh370, even traveled across asia, meeting victims families. Today he said his interest drew him to the beach. I wanted to go out to a place where debris washes ashore from the open indian ocean. My heart was thumping. There was anticipation. There was excitement. There was feeling. Reporter while the primary search zone is still thousands of miles away, marine experts arent surprised debris has turned up on the other side of the ocean. The ocean is much more unpredictable and complicated than a straightflowing river. You get swirls. You get big waves. Reporter even if investigators conclude the debris is from mh370, it wont tell them where the rest of the plane is. The search remains focused some 3,500 miles to the east. Lester. Tom, thank you. A surprise announcement today from american soccer hero brandi chastain. So many remember her icon meteoric world cup victory celebration, now retired she says after years of taking hard hits, she will donate her brain to science, raising awareness about the threat of concussions to women and girls. And that its not just a concern for guys playing football. Nbcs erica hill has more. Reporter the woman behind one of the most icon meteoric moments in sports history is hoping to leave a more lasting legacy. Pledging today to donate her brain for research. Chastain spoke to nbc news about head injuries last november. Wh when you hear things like cte, traumatic brain injury, these are real. These are longlasting, and what we cant do is we cant study the brain while somebody is alive. Reporter her brain will go to researchers at boston university, studying chronic, traumatic, encephalopathy or cte, and a possible link to concussions. The lab has 307 brains. Only seven are from women. We really dont know about cte in girls sports or in womens sports. We need more specimens. We need more ways to diagnose is it. Reporter chastain, who retired from sker in 2010, estimates there were probably half a dozen times she shook off possible concussions from heading the ball. Girls soccer has the second highest number of concussions among high school athletes. With female players suffering 40 more than their male counterparts. Now a mom and coach, chastain works with u. S. Soccer last year to change the rules for heading in youth leagues. As a coach and a soccer ambassador, i have to do whats right for the safety of the players. Reporter continuing her commitment to the game and its future. Erica hill, nbc news, new york. A criminal investigation has been launched over a troubling scene caught on tape in baltimore. It shows a School Police officer slapping a young man in the face multiple times and then kicking him. Its just the latest incident raising questions about the use of force among baltimore law enforcement. Nbcs ron mott has the story. [ bleep ]. Reporter tonight an investigation is under way in baltimore over this foursecond cell phone video showing a School Police officer slapping and kicking a 16yearold boy while a second officer looked on. As a parent of a Baltimore City school student, i was appalled by what i saw. Reporter the mayor, whose city is closely watching a series of criminal trials of Police Officers in the death of freddie gray, sounded exasperated by another policeinvolved controversy. Officials say the two officers were responding to a report of school intruders, but a lawyer for the tenth grader and his family told nbc news, he is enroled as a stungt there. The child and the family want to keep their names private. Hes a minor child. He was injured, and his family is traumatized by what happened. In 2014, another Baltimore City schools Police Officer was seen on camera hitting a female student with a baton. The officer later pleaded guilty to assault. The City Schools Police chief says hes also troubled by what he saw. According to our use of force, definitely Excessive Force was used. In a statement, the States Attorneys Office says it takes this matter very seriously and is working with School Police to investigate. Those forces operate separately. Law enforcement in baltimore once again making headlines. Ron mott, nbc news. Still ahead tonight, slashing doctor bills by thousands of dollars. The website that makes finding discounts on medical services as easy as booking the cheapest flight online. Also story time. Kids testing out their reading skills to an audience thats all ears. There is a new way to com blatt the skyrocketing cost of doctors bills and its as easy as a few clicks on the computer. A startup that is saving thousands by letting them browse the same way you might look for a bargain Airline Ticket online. Olivia stearns has more on our series, the price you pay. Reporter every fall, John Wakefield goes hiking with his buddies out west. But last year his back was hurting, so he decided to get an mri before the trip. I wasnt going to be caught in the woods with, you know, back issues. Reporter in tampa where john lives, an mri costs on average 1,700. With his insurance deductible, john would have had to pay all of it out of pocket. But then he found an amazing deal. I paid 450. Reporter john used a new online marketplace called save on medical. Its almost like expedia for medical care. Reporter heres how it works. Simply choose your procedure, enter your zip, and a list of providers pops up alongside ratings, revuds, and most importantly, price. Matt sha nierd is the ceo of save on medical. They want to pay for the howard johnson, but they want to stay at the ritzcarlton. Reporter at his offices in chicago, he shows me just how much prices can vary for an mri in one neighborhood. The typical price in the area is 1,509, and the average patient can save 69 . So how did you get the providers to bring down their prices . So theyre doing that because they want to fill their excess capacity. Same way in hotels and in the travel industry. Reporter save on works in 39 states. So far theyve helped out 30,000 patients, each saving about 1,000, mostly on mris, cat scans and mammograms. As for john, its a lot of extra money and a little bit of extra peace of mind out on the trails. Until now, consumers really have been in the dark about health care costs, but with so many of us seeing our deductibles go up, it really can be worth it to try and shop around and, lester, save on medical is one way to do it. Were back in a moment with a young golfers amazing hole in one that even stunned one of the biggest names in the game. You have to see this. After eight years in office, you might think the obamas would be quick to leave town come january 2017 for a nice long break from d. C. , but the president said today theyll likely stay in washington for a couple of years so sasha obama can finish high school. An incredible discovery in the unlikeliest of places. Seven identical ty cobb baseball cards, more than a century old have recently been uncovered. They were found in a crumb pled old paper bag by a family claning out their late great gafrs home. It was somewhere in the south, but the family wishes to remain anonymous. Experts have verified the carts authenticity, and they value them at over 1 million. Some golfers wait their entire lives for a hole in one. Taylor kroezer did it at age 11. Taylor hit the very first shot at a brand new par 3 golf course in texas designed by tiger woods, and he made it count. Sinking a hole in one and stunning tiger himself. A grinning taylor then put his club back like it was no big deal and got a bear hug from the master. When we come back, dogs and kids building friendships with books and hugs. Caught on newly installed camer. Plus, easing overcrowding bart. The new incentives for riderswi. Next close the news is next. Finally tonight, a story about the power of reading that combines two kinds of tales, the tails that we find in books, and the tails our Furry Friends wag with delight. Nbcs joe fryer introduced us to Young Readers with an audience thats eager to sit and stay for the next chapter in tonights making a difference. Hi, butdy. Reporter when youre a shelter dog, you really are your own salesman. For a timid pup like biscuit, thats not always the easiest job. Most dogs who are in a shelter setting are scared and frightened and anxiety ridden and they show signs of stress. Which is why the Humane Society of missouri is pulling out every trick in the book. Look at all these angels. Reporter at the st. Louis shelter, kids volunteer their time reading to pets that are waiting for a good home. They call it the shelter buddies reading program, an idea that started around christmas and quickly took off. I personally love animals. Theyre my favorite things in the world. Reporter the children are actually trained to seek out anxious dogs by reading their body language. And its amazing to see the reaction of these dogs. In almost every situation, they come from the back to the front to greet the kids. The more these dogs learn to engage with people, the better their chances of adoption. I think they really enjoy it because theyre getting to interact with people. Reporter and the kids get something out of it too. Theyre learning empathy. A winwin situation thanks to an unconventional partnership. Even biscuit is looking a lot more confident. One of many precious pups ready to close the sale and make a lifechanging connection. Joe fryer, nbc news. We want to tell you that biscuit is still at the shelter and up for adoption at the Humane Society of missouri. But i have a funny feeling not for long. Thats going to do it for us on a thursday night. Im lester holt. For all of us at nbc that brea camera. Weve just obtain that. Breaking news at the county jail in san jose. An inmate brawl caught on camera. Weve just obtained the Surveillance Footage as that jail remains on lockdown. Good evening and thanks for being with us. Im raj mathai. And im Jessica Aguirre re. This brawl was caught on camera. The sheriff purchased and installed just last night. Nbc bay areas Michelle Roberts is at the county jail. Michelle i understand the sheriff just released the video. Reporter yeah. It was certainly a hectic scene inside. Take a look at this video. Just released in the last half hour by the sheriff. This happened at about 3 00 this afternoon. Its tough to see but you can see. Several people throwing punches, guards and inmates running. At the end of the video a guard uses pepper spray to take someone down. Other inmates are lying on the ground. 30 inmates were in this common area at the time. And it looks like about half were involved in the fight. Im told medical staff is here treating people for some minor injuries. Sheriff lori smith installed these cameras just last night. She bought them with her own money after the county said it would take two years and 20 million to get it done. Heres what she had to say just a short time ago. Im really glad thought did. It will give us the opportunity to see what actually happened. Well be able to see who was the aggressor, who was assaulted, who was involved in the fight. The sheriff says this shows the importance of surveillance cameras. And she ds