At a funeral Friday, friends and relatives of University of California Berkeley football player Ted Agu agonized over a promising scholar and athlete gone too soon.
His sister, Doris Agu, said she was still struggling to accept that her younger brother was gone.
"You never asked for too much," she said, addressing her sibling. "You always gave your best. You made all of us so proud."
Ted Agu, who graduated from Frontier High School in 2010, died Feb. 7 shortly after cutting short a routine training run with his teammates. Agu, who played on the Bears' defensive line, was 21.
An autopsy was conducted to determine a cause of death. Results are still pending.
Citing an anonymous source, CBSSports.com reported that the young athlete had tested positive for the sickle cell trait, but the university and the hospital that treated him have not confirmed that due to privacy rules.
The Agu family declined to be interviewed.
More than 500 people crowded into services at St. Philip the Apostle Church Friday to honor a young man universally remembered as kind, talented and respectful. Among those in attendance were two bus loads of university students who rode down from Berkeley.
Ted Agu was born premature to Nigerian immigrant parents, but grew into a strong, towering athlete who hit the books as hard as he hit rival players on the football field.
The packed church was a testament to Ted Agu's character, several speakers noted.
"He was so charismatic, so friendly, so nice, that everyone wanted to be around him," said older brother Kency Agu.
After graduating from Frontier, Ted Agu joined the Cal football team as a walk-on freshman, but he eventually earned a scholarship and would have been a fifth-year senior in the fall. He was pursuing a pre-medical degree.
Agu's unexpected death stunned classmates at Cal, where he was a bright student who mentored younger athletes.
"I wanted to meet Ted's parents and family at our graduation," said Omega Psi Phi fraternity brother Isaac Lapite. He never expected to meet them at a funeral, he said.
But Agu was in the church in spirit, Lapite said, and would remain with him always.
"You climbed the climb, man," Lapite said, nodding toward his friend's casket. "You're up there now. It's our turn."
Frontier classmate Amir Ahmed urged mourners to tell the most important people in their lives that they love them because one never knows what the future holds.
His friend "knew I loved him. He knew it until he took his last breath," Ahmed said, adding that that knowledge was a comfort in the darkness of grief.
The NCAA mandated sickle cell screening for athletes in 2010 after a series of sudden deaths among otherwise healthy people with the genetic condition.
Sickle cell disease is a blood disorder that causes misshapen red blood cells to clot, leading to chronic pain and sometimes death.
People with sickle cell trait don't have the disease, but carry a gene that could produce children with the disease if the other parent is also a carrier.
Most people with the trait go their whole lives without any symptoms, but in rare instances they can experience complications similar to those of people with sickle cell disease.
Generally the trait is only harmful with extreme physical exertion, dehydration, or when there is low oxygen in the air, as is the case at high altitudes. Problems can also surface in increased pressure conditions such as those experienced while scuba diving.