SPRINGFIELD -- When the father of former New England Patriots tackle Ronald J. Brace III took the microphone at St John's Congregational Church to eulogize his son, he told a packed sanctuary that, despite media reports of a heart attack, it is not yet known what caused Brace's death at age 29.

But Ronald J. Brace, Jr. did have his own suspicion: brain damage from his son's days on the gridiron.

"This concussion stuff is serious. Ron had an extraordinary amount of concussions," Brace Jr. said. "I believe the concussions had something to do with his death."

Brace, a Springfield native, Boston College football star and second-round Patriots draft pick in 2009, died at his Springfield home on April 23. The cause of death has not been officially released, though the Boston Globe reported that Brace had suffered an apparent heart attack.

His father said he could not say for sure how his son died, but that Brace had shown symptoms of his frequent concussions prior to his death. He had fainting spells and had crashed his car, Brace Jr. said. Once, Brace collapsed in a CVS, he added.

Brace, Jr., wearing his son's jersey, said he was the one who found Brace dead. At first, he looked like he was sleeping, Brace Jr. said.

"He looked so peaceful in his face, but when I touched him to try to wake him up he was cold," he said.

Brace's early passion was for art, not athletics, his father said. But he joined the track and field team his freshman year at Burncoat High School in Worcester and excelled at shot put, launching an All-State sports career. He won a football scholarship from Boston College, and was selected with the New England Patriots' second pick in 2009.

"That was a dream," his father said.

Brace's aunt Rhonda Brace said that Brace's affinity for charitable work and helping others was evident from when he was a child, long before he returned to Springfield to help rebuild a home after the 2011 tornado. She recalled one outing when Brace was eight years old, and he convinced her to give money to a boy asking for change outside a convenience store.

"That told me then that Ron had a big heart," Brace said.

The link between concussions and early death for football players has drawn national scrutiny, with media investigations casting a critical light on both the NFL's treatment of its players and its research into concussion frequency. In 2012, a study found that 34 deceased NFL players suffered from chronic traumatic encephalopathy, a brain disorder caused by repeated head trauma.