A prosecutor has said that “no one is above the law” as he urged jurors to convict US President Joe Biden’s son Hunter on charges that he lied about his drug use when he bought a gun in 2018.

The evidence is “overwhelming” that Hunter Biden knew he was in the throes of a crack addiction when he marked on a mandatory gun-purchase form that he was not illegally using or addicted to drugs, prosecutor Leo Wise told jurors in his closing argument.

The prosecutor acknowledged the intensely personal evidence that laid bare some of the darkest moments of Hunter Biden’s drug-fuelled past.

That included emotional testimony from his former romantic partners, personal text messages and photos of him holding a crack pipe and partly clothed.

“The evidence was personal. It was ugly, and it was overwhelming,” Mr Wise said. “It was also absolutely necessary.”

Mr Wise pointed to text messages that the prosecutor said showed Hunter Biden trying to make drug deals on the day before the gun purchase and the day after.

“He knew he was using drugs. That’s what the evidence shows. And he knew he was addicted to drugs. That’s what the evidence shows,” the prosecutor said.

Earlier, Hunter Biden smiled as he chatted with members of his defence team and flashed a thumbs-up to one of his supporters in the gallery after the final witness – an FBI agent called by prosecutors in their rebuttal case.

Several family members – including first lady Jill Biden and the president’s brother James – sat in the first row of the courtroom in Wilmington, Delaware.

At one point, Hunter Biden leaned over a railing to whisper in his mother’s ear. She has sat through most of the trial, missing only one day last week to attend D-Day anniversary events with the president in France.

Hunter Biden has pleaded not guilty to three felony charges stemming from the October 2018 purchase of a gun he had for about 11 days.

He has accused the Justice Department of bending to political pressure from former president Donald Trump and other Republicans to bring the gun case and separate tax charges after a deal with prosecutors fell apart last year.

Hunter Biden’s lawyers last week called three witnesses – including his daughter Naomi – as they tried to show that he did not consider himself an “addict” when he filled out the form.

Both Hunter Biden and the prosecutors scanned the jury as US District Judge Maryellen Noreika instructed them on the law. Some jurors took notes with yellow pencils, and many followed along with the judge’s instructions, turning pages as she read aloud from the bench.

The case has put a spotlight on a turbulent time in Hunter Biden’s life after the death of his brother, Beau, in 2015.

Hunter Biden’s struggles with addiction before getting sober more than five years ago are well documented. But defence lawyers argue there is no evidence he was actually using drugs in the 11 days that he possessed the gun. He had completed a rehab programme weeks earlier.

Joe Biden said last week that he would accept the jury’s verdict and has ruled out a pardon for his son.

Last summer, it looked as if Hunter Biden would avoid prosecution in the gun case altogether, but a deal with prosecutors imploded after US District Judge Maryellen Noreika, who was nominated to the bench by Mr Trump, raised concerns about it.

Hunter Biden was subsequently indicted on three felony gun charges. He also faces a trial scheduled for September on felony charges alleging he failed to pay at least 1.4 million dollars in taxes over four years.

If convicted in the gun case, he faces up to 25 years in prison, though first-time offenders do not get anywhere near the maximum, and it is unclear whether the judge would give him time behind bars.