Rik Zortman, who became known for using running to honor his son and other children battling cancer, was arrested Sunday in Iowa and faces a felony charge of child endangerment and willful injury, the Pottawattamie County court's office said.
Zortman originally was booked on a charge of domestic abuse assault in Avoca, Iowa. Prosecutors, however, changed it to the higher, Class D felony charge, the court's office said.
In 2017, eight years after his 3-year-old son died of brain cancer, Zortman had been tinkering with his phone's GPS when an idea hit him: He'd use his daily runs through town to spell out his son's name. He sketched out the name on a map and ran each letter until "Armstrong" was formed.
When he posted a screenshot of his run on Facebook, hundreds of comments started pouring in. He began to fulfill all of the requests and ran names of kids battling cancer. By the end of 2018, he had run more than 475 names in eight U.S. states.
Details of the incident for which he was arrested Sunday have not been made public since it involves a minor, the court's office said.
Zortman said the incident in question was an accident. During an argument with his wife, Kellie, he said, he slipped on some clothes and knocked into her. She fell down the stairs, and her 12-year-old son called 911 because he thought Zortman had pushed her.
Kellie Zortman declined to comment.
Zortman and Armstrong's mother, Lindsay, got divorced soon after Armstrong died. He is now married to Kellie.
A preliminary hearing has been scheduled for April 29.