AUSTIN, Texas — A man was arrested in the beating death of a passenger riding in a car that struck and injured a toddler, and more arrests were likely, police said.

Kurtiss Colvin, 20, was being held yesterday on felony charges of manslaughter and theft and a misdemeanor charge of assault, police said. Bond was set at $215,000.

David Rivas Morales, 40, died of blunt-force trauma to the head on June 19 after being attacked while trying to protect a driver who had bumped a toddler, authorities said. The child was not seriously hurt. Police Sergeant Hector Reveles said witnesses told investigators that Mr. Colvin, a Golden Gloves boxer, hit Morales at least once and took his wallet after he was incapacitated. Police “believe he was one of the primary participants in the assault,” Sergeant Reveles said.

Mr. Colvin was arrested Tuesday. An official at the Travis County Jail said records did not list an attorney for him.

Morales had just been dropped off at an apartment complex when the person who had given him a ride struck a 2-year-old boy, police said. The driver got out of the car to check on the child and was confronted by several people. When they attacked the driver, Morales tried to intervene and was also attacked.

“The investigation is definitely far from over,” Sergeant Reveles said. “We have talked to a lot of people. And we believe there are several more people that are involved.”

The day after the attack, police backed off their initial descriptions of an angry mob beating Morales to death. They now believe there were four to five assailants.

Police also minimized any connection between the beating and a nearby festival celebrating Juneteenth, which commemorates Texas slaves getting the word that they had been freed.