Gavin Rupp, the hospice patient who threw out the first pitch at Nationals Park earlier this season, died Tuesday afternoon after a three-year fight with brain cancer, a Nationals spokeswoman confirmed. He was 13.

In June, doctors informed Rupp and his family gioblastoma cancer had returned to his brain, and the location of the tumor made it inoperable. The Nationals learned about Rupp’s condition through his participation in Kyle’s Kamp, a youth baseball tournament that raises money for Children’s National Medical Center’s pediatric cancer research.

On July 5, Rupp came to Nationals Park with his family. Nationals coordinator of community relations Kyle Mann asked Harper if he could spend a few minutes with Rupp. Harper spoke with him for an hour and gave him signed bats and other equipment, including the hat off his head.

“I can’t say enough. A guy who is 20 years old, to take that much time,” Gavin’s father, Chris Rupp, said at the time, his voice quivering. “When I was 20 years old, I didn’t have that maturity, to do what he just did.”

After the game that night, Harper called Rupp “a hero” on his Twitter account. At the Home Run Derby, players stood with names of loved ones on placards as part of MLB’s Stand Up 2 Cancer campaign. Harper wrote Gavin Rupp’s on his placard.

Back on July 5, Gavin’s father warned him not to throw from the mound, because he may not have the strength. Gavin played shortstop and pitched for his team right up until cancer sapped his strength. He did not listen to his father. With his dad holding up a camera from near the on-deck circle, Rupp threw out the first pitch from the mound. It landed in Harper’s mitt.

For more information about Kyle’s Kamp or to make a donation, click this link.