Last Oct. 12, Dave Stevens slipped his sneakers on for a 90-minute run through the Dallas morning, a chance to clear his mind before heading to his job as an engineer. Every day he wrestled with small, knotty problems to solve larger ones, and most of his General Electric co-workers agreed that his designs were elegant in their simplicity, which was also a good way to describe Dave. He was quiet insofar as he chose his words carefully and had a spare, dry wit. But he also had a free-spirited streak and had recently begun looking at farmland in Oregon so he could raise livestock with his wife, Patti. It was his vision, at age 53, of an early retirement.

Dave also ran to train for the Dallas Marathon, just eight weeks away, aiming to beat his 3:27:03 time from a year earlier. Every so often he would take Patti, speeding ahead before turning back because he didn't like her running alone. But he was solo this morning, looking forward to gauging his pace.

Just before 7 a.m., Dave parked at the trail entrance in Valley View Park, threw his wallet into the glove compartment of his SUV and set off on his run. The sun was still half an hour from rising, but early birds getting in their Fitbit steps were already crowding the path. His favorite stretch of the course followed White Rock Creek through a collection of parks before emptying into a lake bordered by well-heeled homes. Once he passed Anderson Bonner Park, it would be a straight shot through Harry Moss Park until he got to West Lawther Drive and the mouth of the lake loop. There, he'd make his way around the wooden boardwalks with their picturesque views before starting on the return trip.

The temperature was perfect, still in the 70s, and as he started the course, he gulped in the fall air. About an hour later, he was two-thirds through his run and about to pass under the stone bridge that runs above Walnut Hill Lane when something caught his eye.

THOMAS JOHNSON RAN to clear his mind too. As long as he could remember, his legs had taken him places. They carried him around the Dallas borough of Oak Cliff, past trouble on the corners and to sports and church programs. As his athletic talent became evident, he stepped up to bigger stages, like the Junior Olympics in Eugene, Oregon, where at age 9 he set a world record for his age group in the long jump. There was a lot about Thomas that made people want to be around him: the ease he had with himself, how he helped other kids and was unfailingly polite. The Friday night lights of suburban Dallas also revealed a young man whose mother had instilled in him a desire to see a broad world -- the kind a good education would bring. By 2012, he'd become the fourth-ranked football recruit in the state, and when he arrived at Texas A&M that fall, he emerged as one of Johnny Manziel's favorite targets. In just his 10th game, on the road at No. 1 Alabama, the true freshman made a trio of receptions that helped the Aggies past the defending national champion. When he got off the team bus in College Station that night to a raucous celebration, he looked every bit the future NFL star.

But Thomas Johnson never stepped onto a football field again. Instead, three years later, he was hurtling toward Dave Stevens by the stone bridge of Walnut Hill Lane.

AMERICA'S MENTALLY ILL are often overlooked or misunderstood. Interviews with Thomas Johnson's family members, court and police records, and doctors' diagnoses show that those closest to the college star were right beside him when he exhibited strange behaviors and acknowledged hearing voices, yet they all had difficulty interpreting the signs. Some were too ill-informed to understand what he needed, while others saw him through the lens of their own social conscience. Law enforcement officials mainly saw him as a typical drug abuser and figured there was nothing about him that a little rehab couldn't cure. His parents were too busy arguing with each other to agree on a diagnosis.

Three years after he heard his last stadium cheers, Thomas was unemployed, sleeping on friends' couches and, in the rare moments when he opened up, revealing a disturbing side that had already led to two arrests and several months in jail.

"You do know you're talking to yourself," his mother's sister said to him one day as she watched him carry on a one-way conversation. "I'm sorry," he replied, shaking his head with embarrassment.

Those close to Thomas weren't willing to confront the obvious: He was no longer only their problem.

LINDA HANKS IS not quite 5 feet tall, with a soft, sometimes faint voice that understates the long-running battle she's waged with the world. Her mother died giving birth to her, and she grew up in Dallas with three sisters who helped her care for her twin brother, who died at 12 from fluid on the brain. She studied design at a two-year college, and after a brief marriage in the late 1980s, she had a fling with a truck driver named Robert Johnson, who lived in her apartment complex.

Linda, her faith in the Lord strong, proclaimed the two of them blessed when Thomas, their child, was born in April 1994. But the two never married. And as the years passed, Robert and Linda started hurting each other in the name of fighting over what was best for their son.

Linda raised Thomas with a single mother's single-mindedness. Her social services job at a hospital paid for a home in Oak Cliff with a large backyard that she filled with things like tire swings and trampolines, and her happiest memories came from watching Thomas practice the 100-yard dash in their backyard. She taught him to be respectful and not play into anyone's prejudices, and she kept a Bible at arm's reach to answer any questions he had. She made fashion bags at night to sell at work so she could afford the extra cost of track meets and travel games, and she used what she managed to save to take Thomas on trips -- Disney World one year, Washington, D.C., the next.

But to her irritation, Thomas' father, who'd had multiple convictions for theft, remained in the picture. In fact, Thomas lit up with joy whenever he arrived on their doorstep. But by 2005, the price of taking care of Thomas started to overwhelm Linda. She sought bankruptcy protection, citing just $1,753 a month in take-home pay and a lack of child support.

Thomas, a reserved 11-year-old, had already joined a travel football team in Arlington, half an hour away, and was being shuttled back and forth to practice by the team's owner, a wealthy businessman named Ted Ehrhardt. When Ted's son Mitchell learned about Thomas' financial troubles, he volunteered an idea: "Why doesn't Thomas just live with us?"

"It didn't happen overnight," Ehrhardt says. "He'd been visiting and hanging out with my son and spending every weekend with us for three years, doing the things that we do as family."

Ehrhardt, whose company installs and services fire alarm systems, paid for Thomas to attend Oakridge, a prestigious private school in Arlington, and took him on vacations to an island he owns in the Caribbean. A photo from the summer of 2008 shows Ted, a sometime sports agent, his wife, Stacey, and their three sons posing with Thomas on their private beach, all dressed in matching white shirts and khakis.

But as much as Linda wanted Thomas to see the world outside Oak Cliff, she winced when she opened a local magazine in April 2009, a year after he moved to Arlington, and read a profile about her son headlined "Most Grateful Player." The piece included a quote from Thomas, then a freshman, saying that before he met the Ehrhardts, "I was going to school in Dallas and getting into trouble."

Linda was stung by the suggestion that he was better off without her. And she became even more upset when Thomas' father married and moved to a home just 5 miles from the Ehrhardts. In December 2009, Linda drove to Arlington to tell the Ehrhardts she wanted her 15-year-old son back. "They're separating us," she said. "That's not the way it started out, you know?"

Thomas didn't show much emotion as his mother spoke. "It wasn't like he was bawling or crying," Ted recalls. "It was more like, 'My mom needs me. I need to go home with her.'"

Back in Oak Cliff, Linda rented her house so she could move Thomas closer to a magnet school, Skyline High, which has produced eight NFL players since 1994. But the arrangement didn't go as planned. Thomas announced that he wanted to start spending more time with his father and alternated between Robert's home in Arlington and the apartment of his father's sister near Skyline.

Skyline went 9-3 and 14-1 in his two seasons. But as Thomas became an Under Armour All-American wide receiver and Robert took an active role in managing his future, Linda felt more and more isolated from her son. "It was like the vultures were all over him," she says. "It just seemed like every person that came into Thomas' life was trying to control him and exclude me."

She also saw dark forces at work in the recruitment process.

"I know people say black magic don't exist," she says. "But [after Thomas committed] it's like he went to sleep and woke up a totally different kid."

IN THE SUMMER of 2012, Thomas joined a hopeful Aggies team that was entering the SEC with a new coach, Kevin Sumlin, and weapons at almost every position. The only glaring vacancy was at quarterback, and Sumlin chose an obscure redshirt freshman, Manziel, to fill it.

A close friend of Linda's who'd died years earlier and had acted as a godfather to Thomas left him an inheritance for when he turned 18. He wasn't shy about spending it, buying a Chevy Malibu for himself and a Chrysler Sebring for his mother, gifts for friends and an engagement ring for a girl he was dating back home.

On the field, his quiet confidence meshed with Manziel's bravado. When the Aggies rolled into Tuscaloosa on Nov. 10, 2012, they were ranked 15th with a 7-2 record. Alabama was undefeated, but the Aggies scarcely needed three minutes to score their first touchdown. By the end of the first quarter, A&M was up 20-0 in a game it would hold on to win 29-24. Thomas caught only three passes, but each one helped keep a scoring drive alive.

Then, in the aftermath of the Aggies' biggest win in more than a decade, Thomas abruptly left College Station -- a departure that even now is blurred by questions. In the weeks before the game, Thomas had begun comparing himself to the character played by Denzel Washington in The Book of Eli, a post-apocalyptic film about a loner who hears a voice that tells him to deliver a sacred text to a secret location on the West Coast.

According to his roommate, linebacker Michael Richardson, "he was breaking it down to us, and we were like, 'What are you watching, bro?' It was like he [had watched] a completely different movie." By then, Richardson says, "something had spiritually messed him up. He'd sit in his room for hours, reading his Bible and smoking weed. He got distant from everybody. I told him he needed help."

In an interview, Robert Johnson says his son confessed that he'd started smoking synthetic marijuana, or K-2. "I said, 'You've got to be out of your mind,'" he recalls. Thomas' answer -- "Ah, Dad, it's all good" -- hardly encouraged him.

Two days after the Alabama game, the Aggies had a special-teams meeting scheduled at the Bright Football Complex. Because Thomas' Malibu had broken down, Richardson offered to give him a lift. "Nah, it's OK," he said. "I'll see you there." Instead, shortly after 1 p.m., Thomas walked out of their apartment with the television on and didn't come back. The engagement ring he'd bought for his girlfriend was in his pocket; he wanted to give it to her personally. His knapsack was full of Bibles.

There was a Greyhound station 30 miles away, in Hearne, and Thomas walked the entire way. His feet became so blistered that he took off his shoes to walk the final stretch barefoot. It wasn't until the next day, when he failed to show up to a second straight practice, that his coaches realized he was gone.

As Brian Polian, then the Aggies' special-teams coordinator, recalls: "We had law enforcement from different agencies trying to track him down, and no answers." Adds Richardson: "We had cops watching our house. They didn't know if someone had done something to Thomas, and honestly, neither did we."

According to a campus police report, Aggies wide receivers coach David Beaty told an officer that Thomas had "been very religious" in recent weeks. When the officer followed up with Linda, she confirmed that a change had come over her son. In fact, she said, she was concerned enough about the messages he was "getting from the Bible" that she'd brought him to a Dallas-area minister so that Thomas "could better understand" what he was reading.

Linda, however, never referred Thomas to a health professional. And there is no evidence that anyone in authority at A&M did either.

Sumlin and Beaty, now the head coach at Kansas, declined to speak with Outside the Lines. And A&M athletic department spokesman Alan Cannon cited federal student privacy restrictions when saying he "could not comment about a current or former student's medical care." Cannon did say, however, that football players, like all students, receive orientation materials that make them aware of resources on campus, including mental health counseling.

The statewide manhunt for Thomas came to an end three days after his departure, when Robert Johnson found him at the home of a high school friend, talking in a garage. The truck driver tried to coax his son out, but Thomas wouldn't budge. Seeing no other option, Robert called the police. When Thomas spotted a squad car pulling up, he bolted out a back door and started running. "Thomas is crazy," his friend told the officers. "He believes he's Jesus."

With a helicopter searching overhead, Thomas ran to a nearby park, where he frantically called his girlfriend. "I'm hungry, I'm cold. Will you just come see me?" he begged.

Frightened for Thomas' safety, his girlfriend informed detectives, who arranged to follow her as she drove to the park. When he got into her car shivering and disheveled, she drove straight into a prearranged traffic stop. Thomas was taken into custody without incident and transported to a psychiatric hospital, Green Oaks, for evaluation.

After three days of court-ordered supervision, Thomas left Green Oaks with his father. "I said, 'Son, I need you to tell me what's going on. If you don't tell me, I don't know how to help you,'" Robert recalls.

Thomas' reply, he says, was pleading: "Dad, I'm hearing these voices in my head. ... They're just telling me to do different things. Stuff I don't want to do."

A few days later, Robert brought his son to an outpatient facility where, he says, Thomas received a diagnosis of schizophrenia. But in a foreshadowing of his future, Thomas refused medication or long-term care. "He didn't want to go to a hospital because he was afraid he'd be treated like a nutcase," Robert says.

Unless someone petitioned the court to declare him incompetent -- a drastic step that no one was ready to take -- Thomas was free to chart his own course.