Hunter Biden was using crack cocaine shortly after buying a gun in 2018, according to text messages he sent at the time that have been read in court.
Mr Biden, 52, wrote that he was “sleeping on a car smoking crack” in one text sent to his brother’s widow days after the firearm purchase, an FBI agent testifying at his trial has said.
The US president’s son is accused of knowingly lying on a form about his drug use to buy a revolver and ammunition from a gun shop in Wilmington, Delaware.
His defence says he was in recovery at the time, so he was truthful when he wrote on the form that he was not a user of illicit drugs when buying the weapon.
The case marks the first time a sitting US president’s son has gone on trial.
Mr Biden could face up to 25 years in prison if found guilty of all three federal counts in the case.
The trial continues on Wednesday, with more testimony from FBI agent Erika Jensen, who read text messages found on a laptop of Mr Biden that was left behind at a Delaware repair shop and never retrieved.
In her testimony on Tuesday, Ms Jensen said the laptop contained “evidence of addiction”.
The text messages, she said, used coded language for cocaine like “baby powder”, and that Mr Biden appeared to be arranging to buy drugs in the months leading up to him buying the gun.
In one text sent the day after the gun purchase, he told Hallie Biden – the widow of the president’s late son, Beau Biden – that he was “waiting for a dealer named Mookie”.
It is expected that the jury will hear during the trial how Hallie Biden also became addicted to crack cocaine during her brief relationship with Mr Biden after Beau’s death in 2015.
She took the gun from him and threw it in a grocery store bin 11 days after he bought it, concerned about what he might do with the weapon.
Mr Biden is charged with lying to a federally licensed gun dealer, making a false claim on the application by saying he was not a drug user, and illegally having the gun for 11 days. He has pleaded not guilty to all the charges.
Hunter Biden also faces a trial in California in September on charges of failing to pay $1.4m in taxes.
