WATCH: A high school cheerleader and football player's tumultuous relationship: Part 1

WATCH: A high school cheerleader and football player's tumultuous relationship: Part 1

Transcript for A high school cheerleader and football player’s tumultuous relationship: Part 1

Shot in here’s dorah rober. ?????? Reporter: It’s fre band. And everyone is decked out in D and blacrothe centragh bobcatsf Knoxville. Knoxville is a counity.s a lot ofntain folkaround here. B here football is religion. Fdaybody’s excited atchool to S hell we do.it’s what R Hool revols nd. So it’s exciting. Reporter: But no one supports the bobcats quite like the eerleaders. Go bobcats! Eporter: Ande fall of 2014 thereasl whose 14-year-old freshman Emma walker. Emma took cheerl Seri she really loved doing it. U know, it was one of her passions. She loved leg and she ved footballames. High , being a fires chrleader, W that a big deal for her? She had dcoe gymnastics as a G child, a competitive dance. Freshman that made it. So she was very tickled with herself. Orter: At ly 5’4″, Emma’s a petite-sized powerhouse. Bualyful ball energy. Alg T. Emma was very kind and warm hearbut she wagoofy, too, he same time. ??? eroves were nd of like, “Okay, emyo probab sw.” Reporhat spunky eerleader catches T eye ofber 8. Central high’s star player, Riley Gaul. He’s like a speeding bullet on the feel wa the classic jock in high school? No, he was a little nerdy on the side. A little to himself from the outside loo in, U’ was just a Normal guy. Ter: Frien describe him as a jokes raised by his mom and grandparents, Riley seemingly contraction of high ol hes. Thle a top student who loves to play video games. Whatid you think right away of this new boy that she smitten with? Boy next do olite, very nice, the beginning. I thought he was a very nice well red. Reporter: What wereules about dating and going NER let them out normal date. He could come over to the house, ld meet up after ball games to eat, and things like that. They had fun, they seemed lihey reallyikh other. We were happy her that S fod meone thathe liked. Reporter: Her social media with pictures oe perfect pair. Paddleboarding, cuddling, silly in their selfies. W lucky I Riley Gaul and Emma walker couple. U cheerleadeane football player. Repor relatiship like? Of thedinary. He didn’t ly talk to uie, Ju like, oh, he’s shy, like, new friend, it St Normal. But then after a while was when we got kind oncerned. Reporter: Wconcerned u?hat he didreally hav any terest in getting to know frd D of became conolling over wh she did, her activities. He got possessivand more clingy towards her, and, you knwo her do certain things. Reporr: Riley and Emma quickly become that other classic high school couple. Is alwaysreaking upng back together again.when they haghts, were ey big fights? They were really, just Beuse it was usually just like yelling at each other or just like harmful The rationship D not seem all.they argued Cely and tn th sort of made up fiercely.s drama. Alwaysrama with E two. Reporter: He what R? Hmm. S. Rter: And whauld you hat?he decisions maker thatnooyfriend.things gotea intense and bad, he would wait outside her for hero get off an J outside for hours. Wait. Eporter: Did you all relate did feel once for her did E O feel concerned? I told her, aome of the other iends older, we WER just, like, you can do Bette like, we don’t like him. Sh brushed it off,e did her N thing. Reporter: Emma’s friends say the football star becomes ag ke a look E of his Snapchats to his girlfriend. I he you. I hateverything out you. Yo biggest -I’ve ever coey didn’t speak to hhe with a guy shod talk to girl he wasust disrespe Repr: One mesge in rticular as her mom,ill. We on occasion, S one, see your name in the obituary. Reporter: He wrote that to her? Oto her, and quoned him AUT it and said, I was just a, and at started to get many more red flags. Om the hound away her celone, hopinto stop the obsessed ing.itork. Rileyave Emma an ipodch and she texted him throuhe fi Repor sty-gram he nds, there’s a quick apology. Emma, I’m sorry for however I love you more than words can desc Repter: Didou attempt brk them up or advise her to break up? Yes, several times. Ou do that with a teenager, the more you butt heads, the more is going to K in the rig. Because ad a way of isolated making her the only O. Mysterious and frightening third person ente P UT of the blue, someone just.

This transcript has been automatically generated and may not be 100% accurate.

Read More