♪ this is "nightline." >> tonight, expanding the field? the former nfl pro bowler who was never diagnosed with a concussion. >> i mentioned, do you think we should go look at your brain? >> found to have cte after his death. >> he had multiple areas of the brain that were affected on both sides of the brain. >> his widow's mission to inform where she says the nfl is falling short. this as another former player is in the headlines, also diagnosed with cte this week. >> this is a disease that not only destroys people, it destroys their families. plus, missing. a family's desperate search. >> mercedes, she was just a gift. always just had this huge heart of gold are gold.

always. >> the mystery of her last hours and the man she was seen with. >> he's the last person that saw her. and we've tried to question him. and he's basically refused to speak with us. >> abc's michael strahan bringing attention to people who have vanished. mr. clean magic eraser: for a deep down hygienic clean. magic eraser removes the messes you can see as well as more of the dirt and grime you don't. all you do is wet, squeeze, and start erasing dirt and grime all around the house. try mr. clean magic eraser: for a deep down clean. kim is now demonstrating her congestion. save it slimeball. i've upgraded to mucinex. we still have 12 hours to australia. mucinex lasts 12 hours, so i'm good. now move! kim, no! mucinex lasts 3x longer for 12 hours.

small businesses like yours make gift-giving possible. now, comcast business has an exclusive gift for you. introducing the gift of savings sale. for a limited time, ask how to get a great deal for your business. and get up to a $500 prepaid card with select bundles when you switch to the network that can deliver gig speeds to the most businesses. or get started with internet and voice for $64.99 per month with a 2-year price guarantee. give your business the gift of savings today. comcast business. powering possibilities. ♪

thanks for joining us. tonight, the surprising case of vincent jackson. we've been reporting on cte and its impact on nfl players for years now. and while jackson played for more than a decade in the nfl, in her one and only tv interview, his widow tells us he thought he had nothing to fear. now months after his death, she reveals his shocking diagnosis. >> so easy to fall in love with him. just was a big goofball. so humble and obviously easy on the eyes. >> reporter: when linsey jackson talks about her husband vincent, her eyes light up. >> he just was a magnet to be around. he was a gentle giant. >> reporter: a straight-a student, a phenomenal athlete, vincent jackson was an all-american college football player drafted into the nfl, spending 12 years as a wide receiver.

>> fires and is caught, touchdown, jackson! >> vincent was an amazing dad. he loves his kids so, so much. >> reporter: 14 years together and four children. from the outside, the jacksons had it all. >> he had the perfect life. >> he did. >> reporter: but within a few short years, vincent went from having it all to rock bottom. the former pro bowler discovered dead this past february at age 38. >> i think i've blacked everything out. >> reporter: nine months later, in her first and only tv interview since his death, lindsay jackson says it's time to talk about the shock she received when she found out what may have killed him. the most feared letters in football, cte. >> i felt really bad for him. he didn't know he had it. and i think, had he known, he wouldn't have felt so ashamed or alone. no one should have to die in a room by himself. >> reporter: part of her shock,

vincent had never been diagnosed with a concussion. >> it is way more than just concussions, and we don't know that, and we need to know that. it's the repeated head hits. it's the exposure. it's the amount of years you've played. >> so cte is a neurodegenerative disease that's associated with repetitive hits to the head. not just concussions. there's a lot of misunderstanding about that. >> reporter: dr. ann mckee is one of the leading experts on chronic traumatic >> there's shrinkage in the frontal lobes. >> reporter: one of the hardest aspects of cte is symptoms can take years to show up and can often be dismissed or mistaken for something else. >> they may be agitated, impulsive, they may have a short fuse, they may have violent behaviors either physically or verbally. they're often depressed and

moody. >> reporter: the disease can only be officially confirmed after death. it's ranked in stages, from stage i with headaches and short-term memory problems with stage vi including symptoms of dementia, even parkinson's disease. vincent had stage ii. initially he'd taken advantage of retirement, finishing a degree, opening a restaurant. he was cowriting children's looks with lindsey, seen here reading to their own kids. behind closed doors, he was struggling. >> his light kind of began to dim. he was withdrawing socially. the normal stresses of life became really hard for him to handle. >> reporter: lindsey says he turned to alcohol. >> he shared with me once that alcohol made him feel calm and made him feel like himself. and that his brain was really fuzzy and that this made it not fuzzy. >> they drink to make themselves feel better, then they can't stop drinking.

the areas of the brain injury make it very difficult for them to go sober. >> reporter: for years, lindsey thought vincent's struggles stemmed from their busy life. young kids, multiple businesses. but at one point she did wonder, after seeing him forget simple things. >> i mentioned, do you think we should go look at your brain? he was adamant, there was no way that he could be a candidate for cte. he had no idea. >> reporter: lindsey says it's not that they didn't know cte existed, she feels they were just underinformed about how it happens. >> when your husband was alive there were a number of high-profile players diagnosed with cte, including junior seau and others. >> he was friends with junior. very shocked when that all happened. i think when the diagnosis came out, it made more sense to him. because he was in helmet to helmet contact, and that's what vincent thought caused cte. >> reporter: by the time seau died in 2012, cte was well known

inside the league. just a year before, dave shot himself in the chest, leaving a message to his family, asking them to donate his brain to science. they sent to it boston university where dr. mckee runs the brain bank. >> we're getting quite a number of nfl players in the bank. a little over 90% show evidence of cte at neuro >> reporter: doctors have noticed the link between cte and violent behavior. dr. mckee's team revealing former cornerback philip adams had stage iicte. he died earlier this year by suicide after allegedly shooting and killing six people. mckee called his brain damage unusually severe for someone his age and says it may have contributed to his behavior. >> the thing about cte is it makes people unlikeable, it makes them unloveable. they can be depressed, they can be suicida.

this is a disease that not only destroys people, it destroys their families. >> reporter: lindsey says vincent's issues took a toll on their relationship, and about a month before his death they came to the tough decision to take some time apart. >> he had moved to a hotel? >> yeah. that was to kind of take some stress off of his plate. i just always had faith that there was going to come a time where we were going to be able to reconnect. >> reporter: weeks went by, and on february 15th, the sheriff showed up at the family home with horrible news. >> i had been telling the kids and letting them know that dad was really sick, and he's going to get better, and he's going to be back. and here they ae in our living room and telling us that's not the case. >> wa made you want to donate his brain? >> vincent loved to help people. he wouldn't want anyone else to have the ending that he had. >> reporter: the nfl does have a $1 billion settlement agreement for retired players with serious

cognitive decline linked to repeated head trauma and has donated millions of dollars to brain research. both lindsey and dr. mckee say the league focuses too much on concussions and needs to work on awareness and messaging about the cumulative effects of head trauma. >> the nfl needs to overhaul their awareness campaign to concentrate on repetitive head hits that don't rise to the level of concussion. >> reporter: we reached out to the nfl about this story. in a statement the league said, the nfl continues to mourn with the families of vincent jackson, adding, the nfl provides comprehensive mental wellness resources to current and former nfl players and the nfl family. we encourage anyone who may be suffering to seek help. lindsey's focus is on her young kids. three of her four children currently play flag football. but not tackle. >> my oldest son just burst into tears and said, i'm not going to

ever be able to play football, right, mom? and i said -- no. you're not. >> reporter: lindsey says she hopes her husband is remembered for his enormous contributions off the field. >> today we are going to be reading one of our -- >> reporter: like their foundation, jackson in action 83, which helps military families. >> he wanted to be known for helping people. that's just the heart he had. >> what do you miss most about his presence? you said in some ways you feel like he's here? >> yeah, he's totally still here. i miss seeing him with his kids. he was such a good dad. a really good dad. we say, we're the jacksons and we can do hard things. up next, the young woman last seen for a moment on surveillance video, then vanishing without a trace. coming up tomorrow on

"nightline," ben affleck. the evolution of a leading man. >> okay, here we go. ordinary tissues burn when theo blows. so dad bought puffs plus lotion, and rescued his nose. with up to 50% more lotion puffs bring soothing softness and relief. a nose in need deserves puffs indeed. find your rhythm. your happy place. find your breaking point. then break it. every emergen-c gives you a

potent blend of nutrients so you can emerge your best with emergen-c. my hygienist cleans with a round head. so does my oral-b my hygienist personalizes my cleaning. so does my oral-b oral-b delivers the wow of a professional clean feel every day. alright, here we go, miller in motion. wha — wait, wait, is that a... baby on the field?? it looks like it, craig. and the defensive linemen are playing peek-a-boo. i've never seen anything like that before. harris now appears to be burping the baby. that's a great moment right there. the ref going to the rule book here. what, wait a minute! harris is off to the races! we don't need any more trick plays. touchdown!! but we could all use more ways to save. are you kidding me?? it's going to be a long bus ride home for the defense. switch to geico for more ways to save.

mrs. claus the shopping boss here to help you merry savers decorate with the best bargains ever! ross has savings on everything you need to get the party started. because who waits for shipping anymore? or guests?! i love saying yes to more merry for less at ross!

or guests?! ♪ ♪ ♪ ♪ ♪ ♪ visit your volvo retailer for special offers during our holiday safely sales event.

mrs. claus the shopping boss here to help you merry savers find the best bargains ever! when you have the world's longest list you go to ross so you can work that budget and get those savings. i love saying yes to more merry for less at ross. ♪ it is a staggering statistic. of the 540,000 people who went missing last year, most if not nearly all of those cases failed to receive much attention. abc's michael strahan is trying to shine a light on one of those hidden stories of a young woman, hispanic, asian, and now missing. >> reporter: here on this quiet suburban street in dallas, texas -- emiliano and alicia are

getting ready to go on a grim mission. >> from the beginning, it didn't matter if it was a street lead or if it was an anonymous tip or if it was a psychic. we followed the lead. >> reporter: they are frantically looking for their daughter, 26-year-old mercedes clement, missing for a little over a year. it's a search they've been on more times than they can count. >> okay, so the apartment's right here. it's coming up. >> reporter: she was last seen here on october 11th, 2020, captured on this surveillance video walking across the parking lot of the coco apartments. she's accompanied by a man. they're seen going through the courtyard and walking into his apartment. the surveillance camera somehow stops recording from 1:30 a.m. to 8:00 a.m.

mercedes is never seen or heard from again. >> mercedes, she was just a gift. she was always saving her money for the homeless people. always just had this huge heart of gold. always. >> tell me some of your favorite memories of her. >> she did lots of things that were so wonderful. she was volunteering at a youth group and met a young girl who had been assaulted. she came home and she said, mom, she has nowhere to go, we need to foster her. she lived here for two years. >> reporter: police told abc news that shining a light on mercedes' case could bring in tips they desperately need to solve it. take me back to the day that she disappeared. what do you know about what she was doing that day? >> i know about 10:30 that night, she called a couple of her friends. she told one girl in particular she was scared, she needed a ride to her car. her friend said it was eerily

quiet. >> sounded like she was afraid to say something? >> she said hello, and she said, mercedes, what are you doing? she said, i've got to go, and the phone disconnected. and that was it. about the fourth day, when there's no anything, then i got worried. >> what were you thinking? >> well, at first i wondered, is she in a ditch? on the side of the road? then the next day, we got a piece of mail that her car had been towed. and a lot of alarm bells went off for me then. >> reporter: alicia rushed to the tow yard to pick up the car. she was alarmed to find most of mercedes' belongings still inside. >> her purse was in her car. her wallet was in her car. her car key was on the front seat. her bra was on the passenger seat. we just knew something was wrong. >> reporter: alicia alerted the police and spent the next few days desperately retracing

mercedes' last known steps. she went to the coco apartment complex where mercedes' car had been towed from and was able to get that crucial piece of evidence, the surveillance video. she then provided it to the police. >> mercedes' stepdad called us in. and this was done on the 26th of october, 2020. he made a missing persons report. >> reporter: detective patty belue is a detective with the dallas police department. >> mercedes clement's case. victimology, that's very important in an investigation. what i've learned for mercedes is that she's a mother, she has a son, she loves her family. >> reporter: beleu was assigned to the case after it was transferred from missing persons to homicide earlier this year. >> a missing persons is, i want to locate. usually canvass a little bit, then that's pretty much it, and they'll move on.

homicide, then we're out just constantly digging, trying to get information. i believe that we're looking at something has happened to her. >> reporter: the detective said their investigation had led to more questions than answers. one that surveillance camera that stopped recording for seven hours. >> the video we had, we're told that it had a glitch in it. so it stopped recording, unfortunately. and with that, we went to the video company and i asked, is there -- is this something that happens often? they said, not so much. >> reporter: mercedes' belongings found in her car. >> the same purse you see her walking inside the apartment complex with. so either she brought it back or the people who took her put it in the car, and their intentions were to come back to the car, but the car was towed before they were able to do that. >> reporter: the detective said that they have multiple people of interest, including some from her past, where mercedes went

through a period of drug use. >> there you see? >> reporter: at the top of their list is the man mercedes was last seen with on camera that night, 36-year-old tanner lawson. >> and we've tried to question him. and he's basically refused to speak with us. >> reporter: alicia also reached out to lawson for answers, recording their conversation. >> i know you don't think it's significant, i don't know if you need to drive around and jog your memory, you need to sit down -- >> what i have is not significant. >> you need to sit down -- >> to me, there was nothing significant about that day. >> the guy that she was with, he's not talking. he isn't talking to anybody. he maintains he doesn't know anything. >> reporter: losson is currently in dallas county jail on unrelated charges. he did not respond to a request for comment. >> i always keep that because it reminds me of her. >> reporter: now, 14 months after mercedes' disappearance, they fear the trail is starting to run cold. >> i think that the media,

police, missing persons units, there was a stigma around certain people. if they look a little different or if they're living a different life, they don't get treated with that same urgency or that same consideration or that same care. >> reporter: alicia, emiliano, and mercedes' son all have the same wish. >> can you say a prayer before we eat? >> i wish my mom was here. >> what do you want people to know about your daughter? >> my daughter's life mattered. she mattered to us. >> if mercedes is listening right now, what would you like to say to her? >> i am not giving up. i love you so much. i love you so much. i'm just going to keep being strong. and if she's feeling weak, just know that i'm being strong. >> our thanks to michael. up next, with just a little

more than a week before christmas, a santa sighting at a texas hospital. ♪ we wish you a merry christmas and a happy new year ♪ people everywhere living with type 2 diabetes people everywhere living with type 2 diabetes are waking up to what's possible with rybelsus®. with rybelsus®. with rybelsus®. ♪ you are my sunshine ♪ ♪ you are my sunshine ♪ ♪ my only sunshine... ♪ rybelsus® is a pill that lowers rybelsus® is a pill that lowers rybelsus® is a pill that lowers blood sugar in three ways. increases insulin when you need it... increases insulin when you need it... increases insulin when you need it... decreases sugar... decreases sugar... decreases sugar... and slows food. the majority of people taking rybelsus® lowered their blood sugar and reached an a1c of less than 7. rybelsus® isn't for people with type 1 diabetes. don't take rybelsus® if you or your family don't take rybelsus® if you or your family don't take rybelsus® if you or your family ever had medullary thyroid cancer, or have multiple endocrine neoplasia syndrome type 2, or have multiple endocrine neoplasia syndrome type 2, or if allergic to it. or if allergic to it. stop rybelsus® and get medical help right away stop rybelsus® and get medical help right away if you get a lump or swelling in your neck, severe stomach pain, or an allergic reaction. serious side effects may include pancreatitis. tell your provider about vision problems or changes. tell your provider about vision problems or changes. tell your provider about vision problems or changes. taking rybelsus® with a sulfonylurea or insulin increases low blood sugar risk. or insulin increases low blood sugar risk.

or insulin increases low blood sugar risk. side effects like nausea, vomiting, and diarrhea side effects like nausea, vomiting, and diarrhea may lead to dehydration, which may worsen kidney problems. wake up to what's possible with rybelsus®. wake up to what's possible with rybelsus®. ♪ please don't take my sunshine away ♪ you may pay as little you may pay as little as $10 per prescription. ask your healthcare provider ask your healthcare provider ask your healthcare provider about rybelsus® today. about rybelsus® today. did you know some deodorants may not last all day? secret works immediately! and is designed to last for up to 48 hours. with secret, keep it fresh. available in over 10 amazing scents and aluminum free. secret [upbeat acoustic music throughout] [upbeat acoustic music throughout] tums vs. mozzarella stick when heartburn hits,

fight back fast with tums chewy bites. fast heartburn relief in every bite. crunchy outside, chewy inside. ♪ tums, tums, tums, tums ♪ tums chewy bites hey, angie! you forgot your phone! hey lou! angie forget her phone again? yep. lou! mom said she could save up to $400 on her wireless bill by switching to xfinity internet and mobile. with nationwide 5g at no extra cost. and lou! on the most reliable network, lou! smart kid, bill... [laughs] so true. and now, the moon christmas special... gotta go! get a great offer on xfinity internet, and you'll get 12 times the speed for the same price

when you add xfinity mobile. switch today. sing 2.

♪

finally tonight, everyone knows that on christmas eve, santa travels by sleigh. but the week before, when the rush is on, a helicopter is the preferred mode. santa landed the roof of this san antonio children's hospital accompanied by one of his elves. he brought presents, of course, for the patients and gave out hugs and ho ho hoes. he's back at the north pole getting ready for the big event next week. and that's "nightline." see you back here tomorrow same time every day in business brings something new. so get the flexibility of the new mobile service designed for your small business: introducing comcast business mobile.