♪ this is "nightline." >> tonight, july fourth massacre. chilling new details about the shooting at an independence day parade. police say the suspected gunman, now charged with seven counts of first-degree murder, carried out the attack disguised as a woman. >> investigators do believe he did this to conceal his facial tattoos and his identity. >> what authorities are learn from his dark social media posts. >> this is a person who wasn't just crying out for help, this was a person screaming out for help. demaryius thomas. >> nice move! >> the parents of the late super bowl champion make a heartbreaking revelation. >> he suffered from cte station 2. >> why the nfl great suspected he had the disease.

>> he actually thought he had cte. he was like, "i just feel it." there you see the president coming out now -- >> john hinckley jr. one of the most notorious criminals in american history is free and says he's a changed man. why the gunman acquitted of shooting president ronald reagan by reason of insanity says he's no longer a threat. >> can you understand why some would see you as a danger to society? >> not now, no. >> now what he's saying about mental illness and gun control. >> i think there's too many guns in america. >> coming from you, that's quite a statement.

♪ good evening. thank you for joining us. tonight, the suspect in the highland park mass shooting is now charged with seven counts of first-degree murder. law enforcement revealing they have been called to his home three years ago after he allegedly threatened to kill his entire family. and yet he was still able to legally purchae the gun he used to allegedly shoot dozens. here's abc's alex perez. >> he brought a high-powered rifle to this parade. he accessed the roof of a business. a fire escape ladder. and began opening fire on the innocent independence day

celebrationgoers. >> reporter: another city in mourning following another mass shooting in america. 21-year-old robert kremo iii arrested and charged with seven counts of first-degree murder, with more expected to come. authorities believe kremo fired 70 rounds into the crowd from an ar-15 style rifle, which he legally purchased. another legally purchased rifle was found in the car he was driving when arrested. they say kremo spent weeks planning the attack. this picture shows the suspect in disguise as a woman prior to the shooting. >> investigators do believe he did this to conceal his facial tattoos and his identity and help him during the escape with the other people who were fleeing the chaos. >> i could see from my window just everybody hitting the ground, and then running. >> reporter: tony brosio manages gearhead outfitters, which is along the route. seen on this surveillance video, his wife abby, who was outside watching the parade, rushed into

the store after spotting the shooter on a rooftop down the street and yelling at others to take cover inside. >> you don't think it's going to happen to you or somebody that you know or somebody close to you. then it does. my mother-in-law was crawling into the store over my child, and that was just heart-wrenching to see. it's just unreal. unreal. >> even now, knowing what happened, is it still sort of difficult to prepped? >> yeah. yeah, it's incredibly difficult to comprehend. >> reporter: abby was gazed by a bullet, and her father-in-law was shot in the leg -- both are okay. central to the investigating, kremo's social media history. while investigators have yet to determine a motive, we're told the suspect left a trail of disturbing posts online, including depictions of shootings and the video showing what looked to be a portion of the parade route where the shooting took place. >> this is an individual who spent a lot of time online both consuming content, but also

placing content online that should have set off alarm bells for those who saw it. this was a person who wasn't just crying out for help, this was a person who was screaming out for help. >> reporter: authorities revealing kremo had previous run-ins with local law enforcement in 2019. >> a family member reported kremo said he was going to kill everyone, and kremo had a collection of knives. the police responded to his residence. the police removed 16 knees, a dagger, and sword from kremo's home. at that time there was no probable cause to arrest. there were no complaints that were signed by any of the victims. >> reporter: families of the deceased left to pick up the pieces. 63-year-old jacqueline sondheim. 64-year-old katherine goldstein. 78-year-old nicholas saragoza. 88-year-old steven strauss. the young boy left orphaned, his parents 35-year-old irina

mccarthy, husband 37-year-old kevin mccarthy, among the dead. their young son was separated from them during the chaos. he's been recently reunited with his grandparents. tonight the highland park community is left trying to make sense of senseless loss, while investigators look for answers to a sea of unanswered questions. why this place here? why these people? why does this keep happening? >> this is the most volatile, dynamic, and dangerous threat environment that i've pexperien. it is a threat environment which results literally in a mass shooting every several weeks. we are in an epidemic of mass casualty violence. >> our thanks to alex. demaryius thomas seemed to have it all. a decade-long nfl career and a super bowl ring. until his shocking death at age 33. his heartbroken parents donated

his brain to science, and they're revealing what research has found to abc's kaylee hartung. >> thomas against josh norman outside -- >> reporter: for they feel star demaryius thomas, winning the super bowl with the denver broncos in 2016 was the pinnacle of his career. >> super bowl 50, right? i ain't never going to forget it. >> reporter: but his parents say he couldn't enjoy the celebration. >> it was painful but joyful at the same time. because he had took a real bad hit from luke keyingly. he was dizzy, had a real bad headache. he was in pain. but he still wanted to play. >> demaryius thomas is shaken up. >> even hurt, he played. >> because when they won the super bowl and the game was over, he wasn't enjoying himself. he was holding his head down. you know, but he was in pain. >> the headache was already excruciating. >> demaryius thomas, nice move. >> reporter: known as d.t., thomas' death rocked the nfl when he died at 33 years old

last december, less than six months after retiring. >> the denver broncos family lost one of the greatest and most beloved players in franchise history. >> reporter: now in an exclusive interview with abc news, his parents are sharing what they've learned since donating their son's brain to research. >> he suffered from cte stage 2. >> his broken had swollen. it had swollen tremendously. >> reporter: the first cases of cte, chronic traumatic encephalopathy, a degenerative brain disease thought to be caused by repeated blows to the head, were found in the brains of former nfl players nearly two decades ago. did he ever bring up the concept of cte with you? >> he actually thought he had cte. they can't find that out until death. if anyone has cte. so i said to him, how would you know that? he was like, i just feel it. >> reporter: at boston university cte center, dr. ann mckee says she's diagnosed cte in 600 to 700 athletes after

death, from amateurs to professionals, in just about any sport associated with hits to the head. what did you find when you studied demaryius thomas' brain? >> we found what we've seen in so many other players under the age of 34. on the basis of multiple lesions in the frontal lobes and temporal lobes, beginning degeneration of deeper areas of te brain. he was diagnosed with cte stage 2. cte itself does not cause death. you don't die from cte. what cte does is it changes your behavior and your personality. >> reporter: thomas' parents say they saw him struggling in the years leading up to his death. they knew his ten seasons in the league riddled his body with physical injuries, but he was experiencing deeper pain they couldn't explain. >> he was paranoid all the time. memory loss. i saw that as well. every single day he complained about having a headache. >> his mood would change. he would also isolate himself sometimes. it was like, "mom, i don't know what's going on with my body, i

got to get myself together, i don't feel like myself anymore." >> what answers did the cte diagnosis give you? >> when they started explaining side effects, warning signs, that's when the bell started ringing. when they said it i was like, "man he was doing that, he did that too." i could have done more. >> a lot of families have tremendous guilt, but the truth is we don't have any specific treatment for cte at this time. these guys suffer in silence. and they have a lot of trouble finding anyone in the medical professional field who actually knows what's going on. >> reporter: in 2021, thomas started experiencing violent seizures which dr. mckee does not believe were associated with cte. but the result of severe traumatic injuries off the football field, including a car wreck and a fall down stairs made of stone. >> he would shake so much, like he couldn't breathe. you know, you could hear him, the wind trying to come out. it got to the point where he was

having three or four, back-to-back. if it wasn't for those seizures, he would have went back playing football. >> i finally came to a decision, to hang it up. >> reporter: unable to get his seizures under control, last july thomas announced his retirement. >> he was a very private person. >> yes. >> he didn't want people to know what was going on. >> reporter: less than six months later, after his parents say he suffered another seizure, thomas was found dead in his shower. how did you all weigh the decision to donate his brain to be studied? >> at first, i didn't want to do it. i was against it. then i remember a conversation d.t. and i had where he said that, you know, "mom, if anything ever happens to me, i want to be able to help other players." >> reporter: thomas' parents now hope sharing his diagnosis will help other players. >> there are other contact sports out there that will get your head all time. we're not just putting it on the nfl, we're saying is that, if you have a family member that is

in one of those contact sports, pay attention to the warning signs. >> our thanks to kaylee. up next, my "nightline" coanchor juju chang goes one on one with the man who tried to kill president ronald reagan. lactaid is 100% real milk, just without the lactose. tastes great in our iced coffees too. which makes waking up at 5 a.m. to milk the cows a little easier. (moo) mabel says for you, it's more like 5:15. man: mom, really?

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more than 40 years after the assassination attempt on president ronald reagan, the man who pulled the trigger, john hinckley jr., wants to tell his story. now 67 years old and free for the first time since the shooting, he says he's no longer the same man who committed one of the most notorious crimes in american history. tonight his one-on-one interview with my "nightline" coanchor

juju chang. >> hello, everybody. >> why sit down and do this interview? >> i'm trying to show the public that i'm not the person that i was so many years ago. >> that people shouldn't be judged on their worst actions? >> yes. >> and yet, obviously, you did more than most on your worst day. >> reporter: that day was march 30th, 1981. >> here you see the president coming out now. you just have to watch -- [ gunshots ] there, there -- shots. god. >> reporter: 25-year-old john hinckley jr. tried to assassinate president ronald reagan. >> here they're taking away -- yes, he appears to be blond, he is seized as the suspect. >> reporter: hinckley's shooting spree would make him one of the most notorious criminals in american history. a bullet puncturing president reagan's lung, almost killing him. a secret service agent and

police officer also wounded. hinckley's fourth victim, press secretary jim brady, suffering brain damage, paralyzed for life. john hinckley was charged with 13 crimes. later acquitted by reason of insanity. >> i was the most scrutinized mental patient in america. even my judge said that. >> reporter: and now at 67, he is free. after 41 years under medical supervision. he spent 34 of those years at saint elizabeth's psychiatric hospital in washington, d.c., eventually becoming an outpatient and living with his mother. his medications and movements remained supervised. but all that came to an end with a court ruling this past june. his freedom a test of redemption. at the intersection of gun violence and mental illness. >> i worked hard. i walked the line for 41 years and did everything i needed to do to get my freedom. >> can you understand why some would see you as a danger to

society? >> not now, no. >> why? >> because i'm not. if they want to think i'm the person that i was 41 years ago, yes, i could see that. but that's not the person i am now. >> reporter: just before the assassination attempt, hinckley told us he felt cut off from society. what was going on in your mind? >> i was just totally depressed. totally despairing of my life. i thought i had no -- nowhere to turn. i'd become totally estranged from my family. that was the worst part of it. i was totally isolated. >> reporter: an undiagnosed psychiatric disorder made him obsessed with the movie "taxi driver." >> you talking about to me? >> reporter: about a loner plotting to assassinate a presidential candidate. the film starred jodie foster, who hinckley was stalking in real life. >> i don't know who's weirder, you or me. >> i had the delusion back in 1981 that by shooting the president, i could impress jodie foster. which me saying that now, it's -- it's ridiculous, but

that's what i believed back then. it was in ways like a suicide attempt, just saying, this is it, this is the end of my life. >> reporter: he was diagnosed with five severe mental disorders and found to have nd judgment, ts in reality,insie making him an unpredictably dangerous person. do you ever worry that you might relapse? >> no. i take my meds. you know. even though i don't have to now, i still take my meds. >> i read that you take an anti-anxiety and an antips antipsychotic, is that right? >> yes. >> what makes you feel that you can be trusted? i mean, do you trust yourself? >> i do. >> not to relapse? >> i always feel that the meds help. i still feel that way. >> because a lot of people think, if you were criminally insane, that's incurable. >> it's not incurable. i'm sitting here as proof positive that it's curable. >> reporter: hinckley's crimes back in 1981 changed gun control in the u.s.

in 1993, james brady and his wife, sarah, helped pass "the brady act." and the brady law ushered in a waiting period and background checks. >> right. >> especially with regard to people who were suffering mental illness. >> i certainly don't think the mentally ill should have access to guns. i mean, that's kind of obvious. background checks are good. waiting periods are good. i think there's too many guns in america. >> and coming from you, that's quite a statement. >> well -- i hope it is. because it's the way i feel. >> reporter: there was no background check system when hinckley bought his gun at a texas pawnshop with a fake i.d., a felony offense. though hinckley says he's wanted to apologize for years, he's been prohibited by law from contacting his victims and their families. ronald reagan famously forgave you. what message do you have for the reagan family now? >> well, for the reagan family, for the brady family, for the

families of the other two victims, for jodie foster, i apologize for what i've done, for what i did 41 years ago. i'm truly sorry. i really am. i'm not sure they can forgive me. and i probably wouldn't even blame them if they don't forgive me. if i could take it back, i surely would. and i pray, i pray for the family every night. >> i remember that day as if it was yesterday. >> reporter: danny sprigs was a secret service agent on president reagan's detail, seen here that day. he was uninjured and became hinckley's arresting officer. >> i believe in rehabilitation for individuals for certain crimes. in this particular case, we had two individuals who received injuries that disabled them for the rest of their lives. i wouldn't necessarily say he's earned the right to be free. >> he extended his apologies not just to the reagan family, the brady family, jodie foster, and all the agents on that day. do you accept his apology?

>> i do not accept his apology. because i don't think that's sufficient accountability rendered in this particular case. >> you could see why somebody would be skeptical. >> that's why i'm talking to you, trying to show that i'm not that person anymore. >> do you think you've paid your debt to sew night. >> yes, i do. >> in what way? >> i worked hard to overcome my illness. and i'm trying to give back to the world now through my music and my art. and that's kind of my way of paying back my debt to society. >> our thanks to juju. we'll be right back. here. ruby's a1c is down with rybelsus®. my a1c wasn't at goal, now i'm down with rybelsus®. mom's a1c is down with rybelsus®. (♪ ♪) in a clinical study, once-daily rybelsus® significantly lowered a1c better than a leading branded pill. rybelsus® isn't for people with type 1 diabetes.

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and that's "nightline" for this evening. catch our full episodes on hulu. we'll see you right back here same time tomorrow. thanks for the company, america. good night.