Washington Nationals right fielder Jayson Werth reacts after striking out swinging in the first inning against the Cincinnati Reds on May 21 at Nationals Park. (Katherine Frey/The Washington Post)

The Virginia State Police trooper testified it sounded like a racecar when Washington Nationals outfielder Jayson Werth revved the engine of his Porsche and began speeding down an on-ramp for the Beltway in Fairfax County.

Trooper P.L. Green told a judge he floored the accelerator of his cruiser to keep pace with Werth’s GT3 RS on that day in July. Over the next half-mile, Green said, he tailed Werth at 105 mph, but the player was still pulling away from him. Green pulled him over.

Werth, 35, was found guilty of misdemeanor reckless driving Friday for the July 6 incident, and Fairfax County General District Court Chief Judge Penney Azcarate sentenced him to 10 days in jail.

“Speed kills and does not discern what he or she does for a living,” Azcarate told Werth. “495 is not a racetrack.”

Werth’s attorney, Rodney G. Leffler, said he planned to appeal his client’s conviction, and Werth probably will not serve his sentence before that appeal is resolved. Leffler argued Werth could not have been traveling as fast as Green said and attacked the calibration of the trooper’s speedometer but to little avail.

Werth, who wore a charcoal suit and glasses along with trademark long hair and bushy beard, testified in his own defense, saying he was not sure how fast he was going at the time of the offense but believed it was less than 100 mph.

“It’s possible I exceeded 90 miles per hour,” Werth said in court.

Green said the incident began around 9:40 a.m. on a Sunday. He heard the engine of Werth’s Porsche rev on the Georgetown Pike on-ramp for the Beltway. Werth drove onto the Beltway, and Green said he began pacing the player’s vehicle.

Green testified he pulled Werth over on the exit for the George Washington Parkway a short time later. Green said he approached Werth’s vehicle with his gun unholstered but not pointed at Werth.

He asked Werth what he was doing, and Werth told him: He was “pressing his luck.”

Defense attorney Brendan Harold, of the Harold Law Firm, said the sentence was fairly typical for such an offense in Virginia. Harold, who is not involved in the case, said he expected Werth’s attorneys to seek a jury trial on appeal.

“Typically, a jury does not give jail time in cases involving a defendant driving at a high rate of speed,” Harold said.

Werth plays right field for the Nationals and is signed to a $126 million contract. The team released a short statement after the trial.

“We are aware of the judge’s ruling today,” wrote Mike Rizzo, the general manager and president of baseball operations. “Jayson has cooperated fully with authorities throughout this process.”