Witness in Hunter Biden Trial Gives Intimate Portrait of His Drug Use

In text exchanges between Mr. Biden and a former girlfriend, Hallie Biden, the widow of his brother, Beau, she urged him to seek treatment as he trawled the streets for drugs.

Hallie Biden walked briskly to the witness box, past her brother-in-law and ex-boyfriend Hunter Biden, to chronicle a star-crossed relationship that ended in anguish, her own addiction and, eventually, his criminal prosecution.

Ms. Biden, 50, is by far the most important witness for the government. She is one of the few able to offer a detailed, and intimate, accounting of Mr. Biden’s all-consuming addiction to crack cocaine. He is on trial on charges of lying about his drug use on a form to buy a gun in October 2018, and of illegally possessing the weapon.

Moments after she sat down, prosecutors homed in on what they see as the heaviest blow to Mr. Biden’s defense, in a series of texts showing that he bought and smoked crack in the 48 hours after he purchased a gun in Delaware.

The testimony was intended to nail down a clear prosecutorial timeline, which Mr. Biden’s lawyers later undermined. But it also had the effect of forcing Ms. Biden, a recovering addict, to revisit days of desperation and shame, so traumatic that it seemed to dim her memory. She was clearly shaken, repeatedly scanning the gallery for her new husband’s face among the crowd of gawking reporters.

“It was a terrible experience that I went through,” said Ms. Biden, a former school counselor.

“I’m embarrassed and ashamed, and I regret that part of my life.”