this is "nightline." >> tonight, donald trump with fiery words calling for a ban on all muslims coming to america. stirring a major backlash. and the secret life of the terror couple. new photos of the newlyweds arriving together in the u.s. new accounts from inside the attack. plus "i am cait" for the breakout show "transparent," transgender issues have moved to center stage and"transparent" is sharing that spotlight with an honest look at the triumphs and travels, navigating the journey to a new normal.

way for the relative of tv star kristin cavallari and envelope quarterback jay cutler. authorities looking for clues after michael cavallari's car was found abandoned with the air bag deployed. first the "nightline 5." >> what does it take to stay close to a dad who's oceans away? a box of crayons. a fleet of paper airplanes. a next-door neighbor with a box. and a delivery from overseas. that make the distance disappear. paper and packaging. how life unfolds.

good evening. thank you for joining us. republican presidential front-runner donald trump is stirring major controversy again tonight after calling for a ban on all muslims coming to america. his fellow candidates, other politicians across the aisle, and the muslim community speaking out tonight. we're learning new details about the terror couple. authorities now saying the mother and father were both radicalized and had been so for quite some time. here's abc's cecil yeah vega. >> donald j. trump is calling for a total and complete shutdown of muslims entering the united states. until our country's representatives can figure out what the hell is going on. you have no choice. we have no choice. >> reporter: tonight, this political first. a stunning proposal from republican presidential front-runner donald trump. a ban of all muslims coming to america.

into our country. we have no idea if they love us or if they hate us. we have no idea if they want to bomb us. we have no idea what's going on. >> reporter: the proposal widely denounced by the republican party and trump's fellow candidates. jeb bush calling him unhinged. governor chris christie calling the plan ridiculous. >> this is the kind of thing that people say when they have no experience and don't know what they're talking about. we do not need to resort to that type of activity nor should we. >> reporter: and in a rare move, the chairs of the republican party in three major states -- iowa, new hampshire, and south carolina -- all publicly condemning trump's proposal. the muslim community tonight also with harsh words for donald trump. >> donald trump sounds more like a leader of a lynch mob than a great nation like ours. he and others are playing into

this is exactly what isis wants from americans, to turn against each other. >> if you're going to end muslim immigration to the united states today, what are you going to do with the 7 million muslims that are currently living in the united states today? are you going to send us to internment camps? are you going to talk about final solution? >> reporter: trump's proposal coming a day after president obama called last week's san bernardino massacre an act of terrorism. >> here's what i want you to real. but we will overcome it. we will destroy isil and any other organization that tries to harm us. >> reporter: the president cautioning the country against turning the fight against isis into a war on islam, but he did call for the muslim community to be more vigilant. >> that does not mean denying the fact that an extremist ideology has spread within some muslim communities. there's a real problem that muslims must confront without excuse. >> reporter: extremists like the husband and wife terrorists,

seen here in this newly obtained image by abc news, entering the united states through chicago from saudi arabia in july 2014. it was the bride's first trip t this country and likely their first as newlyweds. just 16 months later, they would carry out a massacre inspired by isis, killed in a wild shoot-out with police after the attack, leaving behind a 6-month-old daughter. the fbi still trying to understand what led to the attack. but today revealing the plot had long been in the works. >> we have learned and believe that both subjects were radicalized and have been for quite some time. now how did that happen in the question we're trying to get at is how did that happen? and by whom and where did that happen? we don't know those answers at this point. we are working with our foreign counterparts to determine as much as we can. >> reporter: investigators also saying they found evidence of preplanning. the couple engaged in target practice at gun ranges in the

one session occurring just days before the mass shooting. tonight the country still grappling with this question -- how could this have happened? the fbi searching for clues to build profiles of each of the shooters. tashfeen malik was upon in pakistan to a prominent family, moved to saudi arabia, and then returned to pakistan for college to become a pharmacist. >> she was upper has, hard working. >> reporter: how this ambitious woman and her american-born husband warped into cold-blooded investigation. >> the brother that we knew was not capable of this. you know, the sister-in-law that we knew would never do something like this. >> reporter: farook's sister and her husband say they never even considered their brother and his wife could be terrorists. >> disbelief, shock, anger. you know, it's like -- it's a bad nightmare. >> do you feel like you didn't

>> no, at this time i feel like he had a double life. i feel like he was very good at concealing everything from all of us. >> reporter: as the fbi discovered during a raid of the couple's southern california home, the two tried to hide their tracks by destroying computers and shredding documents. >> we don't know everything yet. we want to find out everyone who profited from it, financed it. and i'm not saying there is anything like that, but we will leave no stone unturned. >> reporter: now agents are interviewing every member of farook's family. fbi questioned enrique marquez, farook's friend and neighbor, who purchased the two assault rifles used in last week's massacre. he is not being investigated for acts. >> they were very close friends. if anybody in is neighbor neighborhood, enrique was the closest to syed. >> we have several down in a conference room, several down. >> reporter: the stories of

inside that conference room it was four minutes of sheer terror terror. >> i heard at least five or six rounds fired, maybe more. >> reporter: eyewitness accounts moments after the couple sprayed gunfire into a room full of government employees, killing 14 people. >> they came in, burst in through the doors, firing and walking into -- towards the mission of the room, indiscriminately firing the whole time. >> reporter: health department bosses trudy remundo and colewin porter trapped in the conference room, hiding under a table. >> i did poke my head up, probably unwise. i did see the muzzle of the gun go down toward the ground and some shots down where our staff were hiding. >> reporter: one witness telling abc news the room was a large space packed with tables. farook and malik burst in through this door at the center of the room, opening fire, blowing out windows and striking many people at this table.

sitting at earlier, playing trivia games with his coworkers. he left his jacket behind saying he'd be right back. >> i remember thinking he was very tall, he was wearing dark clothing. i remember seeing the rifle slung across his shoulder. >> did you hear anything? did they say anything? >> no. >> i never heard anything. >> i never had heard them speak. i was under the table with some staff where i could see there was a small break in the tablecloth. i just kept looking out. and i just kept looking down. and i just kept hoping that the gunfire would stop. >> reporter: police say the couple unloaded at least 65 rounds. the colleagues never even suspected the shooter was one of their own. until later that night when they heard the name syed farook on the news. >> what went through your mind when you heard that name? >> just -- devastation, that it could be possibly one of our own that would do something like

day with. worked side by side with. it was just devastating. >> it's a complete sense of betrayal. >> reporter: for "nightline," i'm cecilia vega in san bernardino, california. next, how has jeffrey tambor navigated playing his award-winning role in the hit show "transparent"? and the search continues for tv starlet kristin cavallari's missing brother. fortunately, my doctor had a game plan. treatment with xarelto . hey guys! hey, finally, somebody i can look up to... ...besides arnie. xarelto is proven to treat and help reduce the risk of dvt and pe blood clots. xarelto is also proven to reduce the risk of stroke in people with afib, not caused by a heart valve problem. for people with afib currently well managed on warfarin, there's limited information on how xarelto and warfarin compare in reding the risk of stroke. i tried warfarin, but the blood testing and dietary restrictions... don't get me started on that. i didn't have to.

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it's been a year of progress for transgender america.

sharing powerful messages to end hate and violence. they're in good company. actor jeffrey tambor's changing the landscape for transgender people in america with his hit amazon show "transparent." here's abc's nick watt. >> reporter: there is an old adage in the arts. write about what you know. >> are you saying that you're going to start dressing up like a lady all the time? >> no, honey. all my life, my whole life, i've been dressing up like a man. >> reporter: and this is something creator jill soloway knows. it's called "transparent" as in transgender parent. >> when i wro the pilot it was from a small place of trying to make art out of what was happening in my real life. >> reporter: her father transitioned in 2011. >> i had just made my first movie. as tacky as it sounds to have the thought when your parent comes out to you, in the back of

tv show out of all this. that's kind of what happened. >> reporter: that show "transparent" onmazon has jeffrey tambor playing patriarch morton, who late in life transitions to maura. >> she's very real, i like her, she scares the heck out of me, the responsibility of it scares me. but i don't mind my hands shaking. >> reporter: tambor's previously best known for deadpan comedic turns in "the larry sanders show" and "arrested development." for maura, he won a golden globe and an emmy. >> i'veeen given the opportunity to act because people's lives depend on it. >> this season especially, maura's more the gateway character, and just one of the people who's seeking love and freedom and authenticity. >> and the emmy goes to -- >> and the golden globe goes

>> jill saloway, "transparent." >> reporter: "transparent's" bagged 11 emmy nominations. season three was commissioned before season two premiered. for me the secret to "transparent's" success is a beautifully drawn family context with maura's transition just one of related movable parts. for example commitment issues. >> i would not have judged you if you slept with other people -- >> i hope by the end of the season you're going to have done the right thing constantly? >> i'm going to try. josh is going to try. >> he is going to try? >> reporter: the show is changing the tv landscape. and they hope the view of transgender people in america. >> on a plane a guy was coming up to me and he was very -- suit, hair, watch, things like that.

and i went, i'm going to get it. he came up to me and grabbed my hand and he said, thank you. thank you for introducing me to something i had no idea about. >> there are people that don't want me in their house. they don't want me in their bathroom. i don't know what the bathroom discussion is, bizarre. i'm not sure what people think goes on in the bathroom. >> reporter: alexander billings, who is trans, plays friend devina on the show. >> i remember halfway through the season, you and i were rehearsing that song that i still don't know -- off >> i remember pulling you out and i was practically crying. i said, am i doing this right? because it just -- it's a tap, tap, tap, tap, tap. i'm a sys gender male. i've been given this enormous responsibility. but it's my lear.

better experience. >> you know, hamlet doesn't need to be danish. we just need to make sure transgender artists are as included as possible. >> reporter: now viewers have two shows about trans women. "i am cait" on e! and "transparent." >> caitlyn's show, which is a realist show, realism show, then our fictive show. >> you finally make sense to me. >> i, by the way, to the point, i really firmly believe that fiction is the better way to the truth than reality. >> daddy, oh my god! what am i supposed to call you now? >> it's all high five on that one. >> high five! >> reporter: season two premiere now available online with the rest of the season to follow this friday opens with a wedding. i won't say whose. but it is perhaps the most realistic slice of family drama i've ever seen.

>> most shows you would rehearse. we just had the wedding. and filmed it documentary-style. >> wait, wait! >> wait, wait, wait. >> when you know that anything can happen, that's like a slightly dangerous place to be. like there are no rules anymore. >> reporter: there are other trans people amongst the crew and in the writer's room and in the cast. >> sort of celebrating otherness i think. whether it's being queer, being trans, being jewish, being feminist. >> i think because the story is so profound, that it's about family, it's about instruction. >> right. >> it's about inclusion of all kinds of things. >> this is me. >> yeah, i think i remember when i was first writing the pilot, talking to my parent, telling her, i want to make the world safer for you to walk out of your apartment building or hail a cab or stand in the elevator with strangers. there are people when they meet my parent they understand who she is. >> reporter: in the process

>> even if you're highly prejudiced, if you are confronted with a trans person that you fall in love with on television, or a amazon in our case, you cross that person, someone like that, in your path, sometime in your life, you're more likely to have a sense of connection that makes it so that you can even just give that person a smile. >> i hope you feel beautiful. because you are. >> reporter: i'm nick watt for "nightline" in hollywood. and next, law enforcement is still trying to piece together what happened to former reality store kristin cavallari's brother, missing more than a week. ok, we're here. here's dad. mom. the twins. aunt alice... you didn't tell me aunt alice was coming. of course. don't forget grandpa.

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finally tonight, a desperate search is under way for reality star kristin cavallari's brother. the mystery continues after his car was found still running and left on the side of the road. here's my "nightline" coanchor juju chang. >> reporter: tonight a family nightmare for "the hills jirngs starlet kristin cavallari and husband quarterback jay cutler as the search continues for the reality tv star's missing brother michael cavallari. this is where police say they found the 30-year-old's honda civic the day after thanksgiving, 100 feet from the road in a remote area of grand county, utah. his laptop and cell phone abandoned inside. the car still running.

>> the temperatures on the night of the incident were in the mid to low 20s. hostile conditions for somebody that was n properly equipped to be here. could be fatal. >> reporter: authorities tracking credit card receipts to this convenience store about 100 miles from where his car was found. cavallari was last seen here on surveillance cameras whering a green sweatshirt and blue baseball cap as he pumped gas. >> there's been ground teams out in this area covering probably a 15 square mile area. >> reporter: tonight the orange county sheriff's department telling abc news that a michael cavallari was arrested on november 23rd for making criminal threats, posting bond two days later, less than a week before the disappearance. 11 days into what is now a missing persons case, kristin releasing this statement on instagram earlier today. i appreciate all the concern, thoughts and prayers that have been extended to me and my family. we remain hopeful. kristin's husband jay cutler, quarterback for the chicago bears, addressing the situation

>> jay, has it been a tough week, has it been hard to kind of get into game mindset? >> oh, no. i mean, we stay focused. >> reporter: authorities plan to bring in dog teams later this week as the investigation continues. for "nightline," i'm juju chang in new york. >> our thanks to juju and thank you for watching. tune into "good morning america" first thing tomorrow. as always we're online 24/7, on the "nightline" facebook page