morgan brennen spent months investigating this cnbc exclusive, and that's next. >>> an emerging turf battle is underway betwe cities and upstart tech companies like air bnb that have beenapitalizing on the wild west landscape of the share econom it's valued at $31 billion, currently worth most of publicly traded hotel rivals. gigantic growth means big growing pains at the same time. >> air bnb unwelcomed guests is our investigation into that class between illegal short term rentals andtr rted regulations. they've worked with cities o craftthe world reasonable regulations. but not in miami beach, where the fight has no end in site. morgan brennen has that story. >> it's 9:00 on a saturday night, and we're ridingg al with miami beach code compliance. on the look out for illegal short term rentals. >> what are you looking for >> hopefully we can establish contact if it's o determine what is a violation. >> code compliance officer have seen it yl. large nois late night parties in residential neighborhoods. commercial shoots with a home investigated for short termnt complaints. and unwitt

may well be starting up their trade talks once again >> let's get a cnbc news update now with morgan brennenere's what's happening at this hour. on capitol hill senate democrats warning allowing people to print 3-d guns will be a threat to national security. they say it's not about policy but public safety. >> this is part of a long pattern of letting the gun lobby get whatever they want even if safety is at risk, even if terrorists could gain the upper hand he complains about terrorists crossing the border, but he wants to let them have guns, undetected what kind of hypocrisy is this >>> a jury has been selected in the trial of paul manafort on tax evasion and bank fraud charges. six men and six women along with four alternative jurors were chosen it's the first trial to result from special counsel robert mueller's russia investigation >>> and researchers at a university in central mexico say they have successfully harvested stem cells from inside the pulp of human teeth the stem cells could come from baby teeth or surgically removed wisdom teeth and the cells can then be multiplied and fro