law enforcement officer shot in 24 hours. an ambush in st. louis, missouri, a drive-by shooting in sanibel, florida, another officer shot in gladstone, missouri. so far this year 58 officers across the u.s. have been killed by gunfire, compared to 36 such killings all of last year. detective marconi graduated from the san antonio police academy 20 years ago, retired detective roy naylor was right there with him and worked alongside s marconi for 20 years because it wasn't the way somebody should go, especially somebody that was respected as well as he was. >> reporter: ambushes like this one have a chilling effect, naylor says. >> people see this, and they're like, why do i want to be a cop if i'm going to get shot for no reason? >> reporter: minutes ago the san antonio police chief confirmed they arrested 31-year-old otis tyrone mccain, about a without incident. he was with a woman and a 2-year-old child. he was arrested, as i said, without incident for what they called a cold and calculated murder. the mayor said we can all breathe a little easier tonight. lester? >> jacob, thank

. >> reporter: and missouri the nation's lowest tax on cigarettes will vote on raising the tax to 60 cents and use the money to pay for early childhood education. >> how many times have we been told a new tax would mean for money for legislation? >> reporter: surprisingly health care advocates oppose it saying it's too small to cut down on smoking. >> adults every child in missouri deserves pre-k. the taxes more on small cigarette companies that undercut prices on the major brands. pete williams nbc news washington. >>> reminder nbc special election coverage begins at 7:00 p.m. eastern time 4:00 p.m. pacific on tuesday night. >>> promoting a sharp mind and good memory. the surprising thing that could make a big difference. also, bringing back the home-cooked meal and all its alright, did you know i was the mommy slam dunk champion? really? yes, really! don't sound so surprised. alright, here we go. let's hear the crowd. ahhhh! i go to the right. i go to the left. fake 'em out. mama go up, up, up! she did it. -again? you can't avoid gravity. but unitedhealthcare can help you avoid financial

fight proves unsuccessful. >> reporter: and missouri the cigarettes will vote on raising the tax to 60 cents and use the money to pay for early childhood education. >> how many times have we been told a new tax would mean for money for legislation? >> reporter: surprisingly health care advocates generally oppose it saying it's too small to cut down on smoking. >> adults every child in missouri deserves pre-k. >> reporter: big tobacco supports it because the measure would boost taxes more on small cigarette washington. >>> reminder nbc special election coverage begins at 7:00 p.m. eastern time 4:00 p.m. pacific on tuesday night. >>> we'll be right >>> we're back with some intriguing health news. it's well known that so-called good bacteria in the stomach can promote overall health. and now there's a growing belief it may be good for the brain helping everything from mood to memory. it's lead to explosive sales of new supplements called psycho biotics. do they work? dr. john torres takes >> reporter: kim carlisle's kitchen looks like a high school chemistry lab. >> it's like a giant dose

states. nevada, wisconsin, illinois, missouri, indiana, pennsylvania, north carolina, florida, and new hampshire. the democrats have to net four or five seats to get control of the senate, depending on who wins the presidency. but it's going to be a nail-biter of a night. some of these races are exceedingly close. >> and history could be made tonight. how hard is it going to be for whomever the next president is to unite this divided country? >> it's a transformational election. if hillary clinton wins, it will be two terms of an african american in the white house and then hillary clinton. if donald trump wins the republican party? if he loses, does the republican party then become a smaller mostly white blplace that doesn't know where it wants to go and how it wants to get there. but whoever wins, you got to put the country back together again and that means a lot of high temperatures have to be lowered in the next year at least. >> and chuck, some of that healing will have to begin tonight. one of them has to make a concession speech. >> tonight the most important speech is the conc

. >> that's the argument that roy blount is making in missouri. >> i'm jason candor, and senator blount has been attacking me on guns. >> in north carolina, senator richard burr had to apologize after seeming to joke hillary clinton should be shot. >> it's got a picture of hillary clinton on the front of it i was a little bit shocked at that. it didn't have a bulls's eye on it. >> if those candidates republicans will probably keep controlling of the senate but if democrats come out on top, it will be a rise to power fuelled in part by women. like maggie hassan in new hampshire. katie mcguinty leading in pennsylvania and tammy duckworth in illinois. all but assured a victory after this debate moment. >> i had forgotten that your parents came all the way from thailand to serve george washington. >> senator mark kirk forced to say he's sorry for seeming enough voters will split their tickets to help republican candidates. >> and underscoring how much is at stake here, more than 344 million dollars has been pumped into just the top five most expensive senate races. an extraordinary a

the northern plains. we already had blue in the net. it's mostly in areas of idaho. in missouri, we have winter weather advisories issued. in the cascades, 6,000 feet. areas of wyoming. we even have winter storm again the bull's eye will be here through jackson and northern machine mince. that's a look at that time weather ahead, new a look at your closer day ahead. ahead of this storm we have near record warmth, areas in the 70s, joplin near 80 degrees. beautiful in chicago. warmth continues in texas, all through the southeast, where we definitely need some of the rainfall. so a little bit of everything out there we have snow and rd storm. >> that's good news, thank you very much for that. from "star wars," kerry fisher had a relationship with harrison ford and the guy that climbed touch tower in august to protecting the future president's home, a major challenge facing secret service. an in-depth look. that's next.

of your screen. undehi missouri, jason candor could unseat the sitting senator, but if richard burr hangs on to his seat and kelly ayotte in new hampshire, look what happens. it's a 50-50 split. in the senate with the support nomination on the line, with the future of the afford bable care about, so what happens then? whoever's the vice president will be the tiebreaker. making that trip down pennsylvania avenue for every >> lot of drama. thanks very much. if tomorrow's election has many on edge, people throughout the world are paying close attention as well. many expressed concerns about the deep division the election has brought out here in the u.s. and fear about the impact on their countries, including new questions on the fight against i isis. more from richard engel. >> whoever wins, the decisions of the next commander in chief will have a en take the fight against isis, now at its most dangerous phase. street to street. we asked iraqi special forces in mosul to wear body cameras to see what they see. how they're kissed by residents who hate the extremists, how they use bulldoz