John T. Walton, 29, of Philadelphia, an athletic assistant at the University of Pennsylvania and a volunteer youth coach in the city’s Fairmount section, died by suicide Feb. 25 at his home.

“Very tragically, my son's death was by suicide,” said his mother, Mary K. Walton. “There was no history of depression, he was doing well academically, had a strong circle of long-term friends, and no obvious explanation we have discovered. So many people loved him dearly. We are all heartbroken.”

Walton and her son, James, said they decided to go public with the cause of Mr. Walton’s death to shine a light on a kind of suicide that can occur in a moment of impulsivity when all seems well to outsiders.

“He was really on a clear path to becoming someone successful in what he loved doing,” said James Walton. “Everything was going well, he was a year away from getting a college degree. He was very happy and healthy.”

Anthony L. Rostain, a Penn psychiatrist, said he had known Mr. Walton from the time he was young and treated him for ADHD, or Attention-Deficit / Hyperactivity Disorder. “I think that it’s important to warn the public: Don’t think suicide only comes from long-standing depression. This just came out of the blue.

“This came out of some part of him that was highly sensitive to stress," Rostain said. “It was an impulsive act.”

Especially in college students and young adults who carry out self-destruction, the trigger can be anything, Rostain said. “They are feeling trapped and the world is closing in on them, and they don’t see a way out.”

Mr. Walton’s mother and brother said it was unlikely they would ever know what prompted Mr. Walton to commit suicide, but they hoped that their transparency could cause “a greater good to come out of such a tragedy,” as people learn more about it.

Born and raised in University City, Mr. Walton loved sports “from the time he could walk,” his mother said.

He played soccer at the William Penn Charter School, but “baseball was his big thing,” his brother said.

He graduated from Penn Charter in 2008, earned an associate’s degree from Philadelphia Community College, and was in the process of earning a bachelor’s degree in sports administration at Temple University. He was set to graduate this year.

For the last four years, Mr. Walton had worked in Penn’s Department of Athletics and Recreation, juggling the details that make athletic events possible. He gave information to visiting teams and officials; helped schedule games and practices; and assisted the directors of facilities and game management.

Mike Martin, his supervisor, described Mr. Walton as a “great coworker, friend and just a good, genuine person that is hard to find these days.” Martin said he had “a real knack for event management,” of baseball, softball, tennis, volleyball, and soccer games.

Mr. Walton had always aspired to a career in collegiate athletics or professional sports, he wrote in an online profile. He was putting in place the building blocks to realize that dream.

For many years, he was involved in the Fairmount Sports Association (FSA), first as a youth player and later as a volunteer baseball coach and association commissioner.

“John’s athleticism was on display every time he took the field,” said FSA coach and vice president Rich Yoka. “He had a cannon of an arm, a smooth swing, and was a fierce competitor.”

As an adult, Mr. Walton remained involved with the FSA, coaching the boys’ travel teams. “I am extremely proud of the person he grew up to be,” Yoka said.

Volunteering for the FSA, Mr. Walton wrote, “was something I always knew would be part of my life because I grew up playing basketball and baseball there, and I wanted to provide the same guidance and leadership to current youths that my coaches provided me with.”

In addition to his mother and brother, Mr. Walton is survived by his godparents, Charles McCormack and Jane Barnsteiner. His father, James R. Walton, died in 2008.

A memorial meeting for worship will be held at 1 p.m. Saturday, March 16, at William Penn Charter School, 3000 W. School House Lane, Philadelphia. Burial was in Laurel Hill Cemetery.

Donations may be made to the John T. Walton Athletic Scholarship Fund, Box 56143, Philadelphia, Pa. 19130. The fund benefits children who need financial help or equipment to play sports.