Hunter Biden, the son of US President Joe Biden, has been found guilty of three gun charges that could see him jailed.
A federal court jury in the Bidens' home state of Delaware reached a verdict after three hours of deliberations over two days.
They found Hunter Biden guilty of lying on a form when he bought a Colt revolver in 2018, and illegally possessing the weapon for 11 days. Hunter Biden had declared on the form that he was not using illegal drugs when in fact he was a crack cocaine user.
It's the second guilty verdict to rock the US election campaign in two weeks after Donald Trump was convicted of 34 counts of falsifying business records relating to a "hush money" payment to porn star Stormy Daniels.
Hunter Biden's lawyer, Abbe Lowell, said they would "vigorously pursue all the legal challenges available to Hunter".
The federal charges have a maximum prison sentence of 25 years, but legal experts say Hunter Biden is unlikely to receive close to the maximum as a first-time offender, and probation is a more likely outcome than prison.
A sentencing date is yet to be set, but it's likely to be before the election on November 5.
Joe Biden has previously ruled out pardoning his son. In a written statement released after the verdict, he said:
"As I said last week, I am the President, but I am also a Dad. Jill and I love our son, and we are so proud of the man he is today. So many families who have had loved ones battle addiction understand the feeling of pride seeing someone you love come out the other side and be so strong and resilient in recovery. As I also said last week, I will accept the outcome of this case and will continue to respect the judicial process as Hunter considers an appeal. Jill and I will always be there for Hunter and the rest of our family with our love and support. Nothing will ever change that."
Shortly after the verdict, the White House confirmed the president was planning to travel to Wilmington, Delaware, to spend the evening with his son. He was later seen embracing his son at the New Castle National Guard Base, just outside Wilmington, after his helicopter touched down.
Earlier, the president spoke at a gun safety event in Washington DC but did not address his son's conviction. A routine press conference at the White House with his spokesperson Karine Jean-Pierre, scheduled for about the same time, was cancelled.
Biden 'more grateful for support than disappointed by outcome'
Prosecutors had played lengthy excerpts of Hunter Biden's audiobook to help prove their case to the jury. In the book, Beautiful Things, Hunter Biden details his descent into alcoholism and drug addiction, accelerated after his brother, Beau Biden, died from brain cancer in 2015.
Hunter Biden, 54, and his supporters looked devastated as they trailed out of the courtroom after the verdict. Some appeared close to tears. As he left the building, Hunter Biden was flanked by the first lady, Jill Biden, and his wife, Melissa Cohen Biden, each holding his hand.
Later, he released a statement thanking his supporters:
"I am more grateful today for the love and support I experienced this last week from Melissa, my family, my friends, and my community than I am disappointed by the outcome. Recovery is possible by the grace of God, and I am blessed to experience that gift one day at a time."
The first lady had been a consistent presence in court, sitting quietly in the front row in support of her stepson. Her only absence from the trial was to accompany Joe Biden at D-Day commemorations in France last week.
Her attendance was remarked upon in closing arguments, with prosecutor Leo Wise gesturing to the gallery as he told jurors that while they might have seen these people on the news, none of that mattered as no-one was above the law.
The verdict came in too quickly for Jill Biden to make it back to the courtroom, and she arrived as it was being handed down.
Hunter Biden was the first child of a sitting president to be criminally tried. It followed an investigation launched by Trump-appointed Delaware US attorney David Weiss in 2018.
After the verdict, Mr Weiss said the case was "not just about addiction", but "about the illegal choices the defendant made while in the throes of addiction".
"No-one in this country is above the law," he said, but later added: "However, Hunter Biden should be no more accountable than any other citizen convicted of this same conduct."
In June last year, Hunter Biden's lawyers negotiated a plea deal with the Department of Justice, to avoid trial on the gun charges by pleading guilty to two relatively minor tax offences.
But the deal collapsed after it was rejected by the court.
Hunter Biden is now also facing tax evasion charges in California, where he is accused of failing to pay $US1.4 million ($2.1 million) in tax between 2016 and 2019. He is scheduled to face trial in Los Angeles in September.
