DOVER, Delaware (AP) — NASCAR driver Kurt Busch will not face criminal charges over claims by his ex-girlfriend that he smashed her head into a bedroom wall and choked her, Delaware prosecutors said on Thursday.

The decision by the state attorney general's office ends the criminal investigation of Busch, known in NASCAR circles as "The Outlaw," over allegations by Patricia Driscoll, whom Busch's attorneys portrayed as a scorned woman who tried to destroy Busch's career after he ended their relationship.

State prosecutors said there was not enough evidence to bring criminal charges.

"It is determined that the admissible evidence and available witnesses would likely be insufficient to meet the burden of establishing beyond a reasonable doubt that Mr. Busch committed a crime during the September 26th incident," the attorney general's office said in a prepared statement.

A spokesman for the Dover Police Department, which investigated the incident and turned over its findings to the attorney general's office, said the department respects the decision, and would have no further comment.

In a prepared statement, Busch thanked prosecutors, and his supporters for standing by him "throughout this nightmare."

"As I have said from the beginning, I did not commit domestic abuse," Busch said. "I look forward to being back in racing as soon as possible, and moving on with my life."

Driscoll said in a prepared statement she was disappointed "full justice" was not served. Driscoll, who made the rounds of television shows after being granted a no-contact order, also suggested media coverage of the case was marked by "distortions" and "sensationalism." She offered no specifics.

NASCAR officials indefinitely suspended Busch last month after a Delaware Family Court commissioner granted Driscoll a "protection from abuse," or no-contact, order, saying the former champion more than likely choked and beat her inside his motorhome at Dover International Speedway last fall.

Busch lost two rounds of appeals for reinstatement before the season-opening Daytona 500, and has missed the first two races of the season, but NASCAR officials said on Monday he has agreed to follow their recommended guidelines to be eligible for eventual reinstatement.

Driscoll said Busch assaulted her in September after she drove from her Maryland home to Dover to check on Busch after receiving disturbing texts. Driscoll said she and Busch argued in the bedroom of the motorhome before he grabbed her by the face and neck and slammed her head against a wall three times.

But she did not file charges until November. She testified that she feared the incident might affect an ongoing child custody battle with her ex-husband in Maryland.