Hunter Biden’s ex-wife and a former girlfriend gave evidence on Wednesday in his gun trial about finding his crack pipes and other drug paraphernalia, as prosecutors sought to show he still had a substance abuse problem when he filled out a form to buy a firearm.

The courtroom grew quiet when Kathleen Buhle, who was married to Hunter Biden, son of US President Joe Biden, for 20 years, walked in.

She said that she discovered her husband was using drugs when she found a crack pipe in an ashtray on their porch on July 3, 2015, a day after their anniversary.

When she confronted him, “he acknowledged smoking crack”, she said.

The trial has quickly become a highly personal and detailed tour of the mistakes and drug use of Hunter Biden, whose struggles have been tabloid fodder for years and were used publicly by Republicans, including in their stalled impeachment effort against the president.

The proceedings are unfolding as the 2024 election looms, and allies worry about the toll it will take on Joe Biden, who is deeply concerned about the health and sustained sobriety of his only living son.

Prosecutors say the photos, testimony and other evidence are necessary to show Hunter Biden’s state of mind when he bought the gun.

Hunter Biden has been charged with three felonies stemming from the purchase of a gun in October 2018. He is accused of 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.

Even before she found the drugs, Ms Buhle suspected that Hunter Biden was using, given that he earlier had been kicked out of the Navy after testing positive for cocaine.

“I was definitely worried, scared,” she said. They have three children and divorced in 2016 after his infidelity and drug abuse became too much, according to her memoir, If We Break, about the dissolution of their marriage.

Ms Buhle remained composed but seemed upset as she recounted how she searched his car about a dozen times for drugs, whenever the children were driving it.

“Did you ever see Hunter using drugs?” defence lawyer Abbe Lowell asked her.

“No,” she replied.

Then prosecutor Leo Wise asked Ms Buhle how she knew Hunter was using drugs.

“He told me,” she said.

Prosecutors also called Zoe Kesten, who testified under immunity and matter of factly about meeting Hunter Biden in December 2017 at a strip club in New York where she worked.

During a private session, he pulled out a pipe and began smoking what she assumed was crack.

Jurors were also shown a photo of Hunter, bare-chested in a bubble bath they shared, but he was cropped out of other images of a crack pipe in a hotel bathroom.

“He was incredibly charming and charismatic and friendly, and I felt really safe around him,” she said. “I remember after he had smoked it, nothing had changed. He was the same charming person.”

Ms Kesten detailed for jurors when she saw him use drugs, buy drugs, talk about drugs or possess drug paraphernalia.

Prosecutors asked her where he stored his drugs and pipes, and she said he kept them in pouches and other places, such as a sunglasses cases.

Under cross-examination, she  acknowledged that she had no contact with him in October 2018, the period when he bought the gun.

Jurors have been shown dozens of pages of Hunter Biden’s memoir, Beautiful Things, written in 2021 after he became sober.

And they heard lengthy audio excerpts from the book, which traces his descent into addiction after the death of his brother, Beau Biden, in 2015 from cancer.

The memoir covers the period he bought the gun, though it does not mention the weapon specifically.

Mr Lowell has said Hunter Biden’s state of mind was different when he wrote the book than when he purchased the gun, when he did not believe he had an addiction.

And the prosecutors must prove he had a drug problem when he filled out the document at the time of purchase.

An FBI agent, Erika Jensen, gave evidence about her job to establish that Hunter Biden had a drug problem when he purchased the gun in October 2018.

Mr Lowell went through a large number of Hunter Biden’s texts to establish that there were few messages that involved seeking or using drugs in the weeks before the gun purchase.

He also raised questions about how the FBI could prove Hunter Biden was being truthful with family when he texted about seeking or using drugs.

And he pointed out several alcohol purchases in October 2018, the month Hunter Biden bought the gun.

Mr Lowell has suggested that references in his memoir to “relapsing” refer to alcohol abuse, not drug use. A drinking problem does not preclude the purchase of a gun.

The trial in the state of Delaware comes after the collapse of a plea deal with prosecutors that would have resolved the gun case and a separate California tax case and avoided the spectacle of a trial.

Hunter Biden has since pleaded not guilty and has said he is being unfairly targeted by the Justice Department, after Republicans criticised the now-defunct plea agreement as a sweetheart deal for the Democratic president’s son.

In Congress, Republicans have for months pursued an impeachment inquiry seeking to tie the Democratic president to his son’s business dealings.

So far, Republican lawmakers have failed to uncover evidence directly implicating President Joe Biden in any wrongdoing.

But on Wednesday, House Republicans accused Hunter Biden and the president’s brother, James Biden, of making false statements to Congress as part of the inquiry.

In the trial, Erika Jensen, the FBI agent, read aloud some of Hunter Biden’s personal messages, including some that came from a laptop he left at a Delaware repair shop and never retrieved.

In 2020, the contents made their way to Republicans and were publicly leaked, revealing some highly personal messages about his work and his life. He has since sued over the leaked information.

Prosecutors asked whether there was any evidence to suggest the laptop had been tampered with, and Ms Jensen said no. But under questioning from Mr Lowell, she conceded there was no way to verify whether it had been altered.

In addition, jurors are expected to hear from the James Biden, who is close to Hunter Biden and helped his nephew through rehab stints in the past.

They will also hear details of how Beau Biden’s widow, Hallie Biden, became addicted to crack during a brief relationship with Hunter after her husband’s death.

Hallie Biden took the gun from Hunter Biden and threw it into the rubbish at a nearby market, afraid of what he might do with it. The weapon was later found by someone collecting cans and eventually turned over to police.

First lady Jill Biden went to court for the third consecutive day to support Hunter, ahead of her trip to France to meet President Joe Biden, who was in Europe to mark the anniversary of D-Day.

If convicted, Hunter Biden 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.