Federal prosecutors have rested their case in the criminal trial of Hunter Biden after calling their last two witnesses to the stand.
One of them, an FBI chemist, testified that a “minimal” amount of cocaine was found in a leather pouch that contained Mr Biden’s firearm.
But the witness said he could not say for sure how the cocaine got there, or who it belonged to.
The US president’s son is accused of lying about his drug use on a form when purchasing the firearm and ammunition from a Wilmington, Delaware, gun shop on 12 October 2018.
Mr Biden, 54, has pleaded not guilty to the charges, with his defence team saying he was in recovery at the time and therefore did not lie on the paperwork.
It is the first trial for the son of a sitting US president. Mr Biden could face up to 25 years in prison if convicted.
On Friday, the prosecution wrapped up its case in a federal Delaware court after calling their remaining two witnesses.
FBI forensic chemist Jason Brewer said he had examined a white residue found on the brown leather pouch that held Mr Biden’s gun, and it tested positive for cocaine.
Jurors heard earlier in the week that 11 days after Mr Biden purchased the gun, it was disposed of by Hallie Biden - his ex-girlfriend and the widow of his late brother, Beau.
Ms Biden told the court that she “panicked” when she found the revolver while clearing Mr Biden’s truck.
She then stuffed it in the leather pouch, wrapped it in a small purple gift bag and disposed of it in a rubbish bin at a local grocery store.
“Are you insane?” he texted, telling her to go back to Janssen’s Market and retrieve the weapon.
It was later found by a man who was rummaging through the refuse for recyclables.
Ms Biden said that she, too, fell into drug addiction after she was introduced to crack cocaine by Mr Biden during their relationship, which began after Beau Biden’s death in 2015, but that she quit using in August 2018.
Now that prosecutors have rested their case, Mr Biden’s defence team will begin calling their own witnesses to the stand.
His lawyer, Abbe Lowell, said the first witness will be Jason Turner, who worked at the gun shop where Mr Biden purchased his firearm.
The second witness will be Ron Palmieri, the owner of the shop.
US President Joe Biden has meanwhile continued his public duties. On Friday, he gave a speech in France on democracy after meeting Ukrainian President Volodymyr Zelensky.
In an interview with ABC News, Mr Biden said he would accept the outcome of his son's trial and wouldn't pardon him if he were convicted.
As the trial got underway this week, Joe Biden said he would not comment as president, but that as a father he felt "boundless love" for his son.
Hunter Biden also faces a trial in California in September on charges of failing to pay $1.4m (£1.1m) in taxes.