A Long Beach trainer who testified on Capitol Hill that he repeatedly injected his former client, ex-Yankees pitcher Roger Clemens, with performance-enhancing drugs, has been charged with driving while intoxicated, according to court records.

Brian McNamee, 48, was taken into custody by Long Beach police Monday about 8:30 a.m. following a minor collision as he pulled his white 2002 GMC sedan out of a gas station onto westbound East Park Avenue, near Long Beach Boulevard, records show.

He was charged with misdemeanor DWI along with operating a motor vehicle impaired by drugs, driving while ability impaired by drugs or alcohol, aggravated unlicensed operation of a motor vehicle, and other violations, all misdemeanors.

McNamee is scheduled to be back in Long Beach City Court on Wednesday. He was arraigned Tuesday. McNamee represented himself at arraignment.

No one answered the door Tuesday at the Long Beach address listed on his ticket. He could not be reached by phone.

McNamee, who was Clemens’ longtime trainer, had identified Clemens as a performance-enhancing drug user in the Mitchell Report, baseball’s report on steroid use in the league compiled in December 2007 by former Sen. George Mitchell (D-Maine). Both McNamee and Clemens testified about the pitcher’s drug use before Congress in 2008 and 2012.

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In 2008, McNamee sued Clemens, a former Yankee right-hander and a seven-time Cy Young Award-winner, for defamation, saying the pitcher slandered him by saying his former trainer lied about injecting him with performance-enhancing drugs in 1998, 2000 and 2001.

Clemens denied the accusations, including under oath during his 2008 congressional testimony, and in 2012 was acquitted of perjury and obstruction charges that stemmed from his denials.

McNamee was the government’s key witnesses, taking the stand for five days in Clemens’ criminal trial. McNamee testified he kept needles and steroid ampules he used to inject Clemens — a key piece of government evidence — to placate his then-wife’s concerns that he would one day take the fall for Clemens’ drug use. McNamee said he gave Clemens 16 to 30 injections in 2000.

In March, McNamee and Clemens reached an undisclosed financial settlement in the federal defamation lawsuit.