Byline: Rachel Weiner and Peter Hermann

A Southern California conservative activist cried and apologized for using a Taser on a police officer outside the Capitol on Jan. 6, in the first interrogation video of a riot defendant released publicly.

Daniel Rodriguez is among those accused of assaulting D.C. police officer Michael Fanone, who was shocked with a stun device as rioters dragged him down the steps of the Capitol. Fanone lost consciousness and was stripped of his badge and gun; he suffered a heart attack and a traumatic brain injury.

Rodriguez, 39, has pleaded not guilty and is attempting to block prosecutors from using his statements to the FBI at trial. At first, he declined to discuss the assault on Fanone with the two special agents who interrogated him just after his arrest in March. But when pressed, Rodriguez suggested he used a Taser on Fanone to keep him from getting more seriously injured.

"I don't know if I tasered him to protect him, but maybe just to, like - so he wouldn't struggle and get hurt, maybe," Rodriguez said. "If they're going to beat him up or injure him or, like - I don't know if they're going to - I don't know what was going to happen to him."

Soon after, Rodriguez broke down, apologizing and cursing himself.

"I'm sorry," he said through tears. "I don't know. He's a human being with children,...