Kent State University freshman football player Tyler Heintz likely died as a result of "hyperthermia," a dangerously high body temperature, following a team workout with the Golden Flashes June 13 at Dix Stadium.

Portage County Coroner Dr. Dean DePerro said preliminary autopsy results showed Heintz, 19, had "a very high body temperature."

As to "what led up to that, we're still putting that together," DePerro said June 14. He said his investigators still are following up with questions and interviews, following the result of the autopsy performed by the Cuyahoga County Medical Examiner's Office.

Hyperthermia can result from exercising in high temperatures and high humidity, DePerro said. The body "stops perspiring" and can't regulate its own temperature, leading to overheating and life-threatening symptoms that can include shortness of breath, nausea or vomiting.

An assistant KSU athletic trainer who called 911 requesting an ambulance on the field at Dix Stadium told an emergency dispatcher Heintz was having trouble breathing and was "in and out of consciousness," according to the call, released June 14 by Kent police.

The caller requested an ambulance to the field at Dix Stadium for "an athlete from a workout, he's having difficulty breathing, in and out of consciousness."

She told the dispatcher Heintz was 18 years old and 300 pounds and said it was the team's second summer practice.

DePerro said the results are preliminary and that other factors may be involved. It may take weeks or months for final autopsy results, he added.

"There are a lot of young boys, girls, men and women who were out in the weather he was and for some reason his body reacted differently," DePerro said.

Heintz' body has been released to a funeral home, he said.

DePerro noted that the final autopsy report and death certificate for KSU football player Jason Bitsko, an offensive lineman from Huber Heights who was found dead Aug. 20, 2014, in his off-campus apartment in Brimfield, took nine months to complete.

His death was a result of cardiomegaly -- an enlarged heart found at autopsy to be approximately twice the size of a normal heart, which led to a significant risk for an abnormal heartbeat, DePerro said in December 2014.

Additional resources, including a University of Washington researcher who also helped probe Bitsko's death, may be utilized in the investigation, DePerro said.

Heintz spent countless hours working in the hot sun on his family farm in Kenton, about 75 miles south of Toledo, according Brent Fackler -- his high school football coach.

On June 9, he worked out with his old high school team back home, completing a series of 110-yard sprints with no issues. He lived a clean life, was in excellent physical condition and was determined to earn playing time as a true freshman offensive lineman for the Flashes this fall, according to Fackler.

"Tyler had a physical, maybe two in the last two weeks," Fackler said. "[On June 9] with us here he ran 14 110s, which is not easy. We run 110 [yards], then they have 45 seconds to rest, then they run another 110 for 14 minutes.

"That's quite a bit of running and Tyler didn't show any problems there. It was my understanding that he did finish the workout at Kent, then he collapsed after stretching. It's just unbelievable. It's devastating."

Heintz reported to Kent State's campus earlier this month along with most of the rest of the football team and started summer classes and workouts June 12. The 6-foot-4, 275-pound lineman was close to Fackler's sons Mark and Brice, who also played football at Kent State, and was thrilled when the Flashes offered him a scholarship last year.

"When Tyler got that offer from Kent State, he was like, 'I don't care if Kentucky offers me or Pitt offers me or whoever, I want to go to Kent State,'" said Fackler. "At his graduation party, that's all he talked about, 'I'm making the traveling team; I'm going to Clemson [for the 2017 season opener]. The kid didn't back down from anything. It's just a crazy thing."

Heintz was all about hard work, both on and off the field, according to Fackler.

"Great kid, great family, a farm family," Fackler said. "You can see where he got his work ethic from. Mom and dad are just unbelievable workers. Tyler was their oldest boy [two sisters and a brother]. He was going to go to college, then come back and run the family farm."

No one enjoyed preparing for football at Kenton more than Heintz.

"We had morning lifting for all of his years here starting in March at 6 a.m.," Fackler said. "He lived quite a distance away, but a lot of times, he was at his truck sitting there in the parking lot waiting for me to open the door.

"He was always the first guy here. Tremendous worker for us -- always a guy that pushed himself. When he was younger, he was a bigger kid, not as agile as what he would become, all because of the hard work he put in."

Heintz was a large young man, but his size and strength came naturally, according to Fackler.

"The toxicology report came back clean when they were still in the hospital trying to save his life," Fackler said. "I didn't expect anything other than that.

"As a high school coach these days, you have to talk to your kids about all of these supplements, Jack's Juice, these Monster drinks and all that kind of stuff. We'd talk to Tyler and he was always like, 'I don't take any of that stuff. He's an old farm boy. Hard work is what got him where he was."

As the father of two sons who played football at Kent State, Fackler feels for head coach Paul Haynes and his staff, who have gone through this before.

In August of 2014, just 10 days before the scheduled season opener, 21-year-old Bitsko failed to show up for a scheduled Flashes morning football practice and was ultimately found dead in the bedroom of his off-campus apartment.

"We just feel so bad for coach Haynes too," Fackler said. "This is two guys in four years and there's nothing he could have done about it. I know [Heintz] was really into this Kent State football team, really bonded with the guys that were coming in and thought an awful lot of the coaches."

Fackler doesn't believe anything Kent State did or did not do contributed to the death of Heintz.

"It happens in every sport," Fackler said. "You have all of these conditions you need to meet, have the water on the field, give your kids a break and I know they're doing that at Kent State. My kids went through the program. The other kids weren't affected, and I'm sure Tyler was in as good a shape as most of the other linemen."

Fackler held a team meeting June 14 at Kenton.

"I sat them down and talked to them about what happened, gave them the information I know," Fackler said. "We had a good conversation. He was the only senior on the line last year, so a lot of these guys played with him.

"I told my players to make sure you give your parents a hug when you come home. We always talk about any play could be your last. You're not thinking about death at that time. You're thinking of injuries and things like that, but it could be the last time on this earth you see somebody as well. Always tell them you love them."

Haynes said Heintz will be missed.

"We are deeply saddened by the loss," Haynes said in a statement. "Tyler was an unselfish young man who exemplifies everything we look for in a Golden Flash. Our thoughts and prayers go out to his family and friends."

Eric Mansfield, executive director of media relations for the university, said a group of KSU student athletes set up a GoFundMe page, "Support for the Heintz Family," to help the family.

"This page is a way for the Kent State community, Kenton community, students and athletics to show our support for the Heintz family in the wake of their unexpected and tragic loss," the GoFundMe page stated.

Heintz was planning to study marketing and entrepreneurship in the College of Business Administration while helping out on the Golden Flashes offensive line on the football field, according to the GoFundMe page.