AUSTIN (KXAN) — A man accused of running over and killing another man with his car in May has been arrested for another road rage incident that police say happened more than a year earlier.

James Derks, 35, was arrested in May after Austin police say he ran over a man whose car he’d been tailgating. Investigators say when the victim, Eric Walz, got out of his own vehicle and walked toward Derks, Derks accelerated toward him, hit him with the car and then left the scene.

When detectives began looking into Derks’ driving history, they found that in the past ten years, more than 40 9-1-1 calls had been made reporting someone driving recklessly or aggressively in vehicles registered in his name.

“We did go back and look at this person’s history, and we’re pretty blown away by the information that we saw,” said APD Homicide Detective Nathan Sexton.

Upon calling some of those 9-1-1 callers back, detectives came across a case in January 2018, in which a woman said Derks pulled out a knife and pointed it at her in traffic when she wouldn’t let him over. The woman eventually pulled into a parking lot to call 9-1-1, and she told police Derks then stopped his vehicle, got out and began running at her vehicle with the knife. The woman told police her dogs began barking from the back of the vehicle, and Derks turned around and left.

Derks was arrested on an aggravated assault charge in connection with that incident on Wednesday after detectives questioned the victim further. His bond was set at $20,000. By Thursday evening, records show he bonded out of Travis County Jail.

Although 9-1-1 calls were made for years, Sexton says they wouldn’t have made their way to detectives, because traffic violations are misdemeanors. Officers only respond to road rage calls if they’re in the area and available, and instances of aggressive driving can be hard to prove if officers don’t catch the suspect in the act.

“If there’s nothing more than a traffic violation at the time, then there won’t be a report written and there’s not necessarily a database of anything that’s collected on them,” Sexton said, adding, “I wish that there was something in place that we could have caught this sooner, somehow, but there really wasn’t any solid case that we ever had to be able to investigate to be able to find this sooner.”

Sexton says he’s concerned because while Derks’ vehicle was impounded after the road rage incidents, his license wasn’t suspended.

“There’s nothing at the moment preventing him from borrowing or renting a car,” Sexton said.

APD can only request an automatic suspension in certain cases. Derks’ charges didn’t qualify. KXAN asked the officials with the Department of Public Safety what kind of circumstances it would take to suspend a license in such a case but had not gotten an answer as of Thursday evening.