WILMINGTON :  The criminal trial of President Joe Biden’s son heads into its final stretch Monday as the defense tries to chip away at prosecutors’ case laying bare some of the darkest moments of Hunter Biden’s drug-fueled past.

Hunter Biden’s lawyers could call at least one more witness when the case resumes in Delaware’s federal court — the first of two trials he’s facing in the midst of his father’s re-election campaign. It’s unclear whether prosecutors will call any rebuttal witnesses before the case goes to closing arguments, and then to the jury.

Hunter Biden is charged with three felonies stemming from the October 2018 purchase of a gun he had for about 11 days. Prosecutors say he lied on a mandatory gun-purchase form by saying he was not illegally using or addicted to drugs.

Hunter Biden has pleaded not guilty and has accused the Justice Department of bending to political pressure from former President Donald Trump and other Republicans to bring the case and separate tax charges after a deal with prosecutors fell apart last year. Hunter Biden has said he has been sober since 2019, but his attorneys have said he did not consider himself an “addict” when he filled out the form.

The case has put spotlight on a turbulent time in Hunter Biden’s life after his brother Beau’s 2015 death. First Lady Jill Biden has watched it unfold from the front row of the courtroom. President Biden was away in France much of last week, and heads to Europe again this week for the Group of Seven leaders meeting in Italy.

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

Jurors have heard emotional and tawdry testimony from Hunter Biden’s former romantic partners and read personal text messages. They’ve seen photos of Hunter Biden holding a crack pipe and partly clothed, and video from his phone of crack cocaine weighed on a scale.

His ex-wife and two onetime girlfriends testified for prosecutors about his habitual crack use and their failed efforts to help him get clean. One woman, who met Hunter Biden in 2017 at a strip club where she worked, described him smoking crack every 20 minutes or so while she stayed with him at a hotel.

Hunter Biden hasn’t taken the witness stand and it’s unclear if he will. But jurors have heard him describe at length his descent into addiction through audio excerpts played in court of his 2021 memoir “Beautiful Things.” The book, written after he got sober, covers the period he had the gun but doesn’t mention it specifically.

 A key witness for prosecutors is Beau’s widow, Hallie, who had a brief troubled relationship with Hunter after his brother died of brain cancer. She found the unloaded gun in Hunter’s truck on Oct. 23, 2018, panicked and tossed it into a garbage can at a grocery store in Wilmington, where a man inadvertently fished it out of the trash.

“I didn’t want him to hurt himself, and I didn’t want my kids to find it and hurt themselves,” Hallie Biden told jurors.

From the time Hunter returned to Delaware from a 2018 trip to California until she threw his gun away, she did not see him using drugs, Hallie told jurors. That time period included the day he bought the weapon. But jurors also saw text messages Hunter sent to Hallie in October 2018 saying he was waiting for a dealer and smoking crack. The first message was sent the day after he bought the gun. The second was sent the following day.

The defense has suggested Hunter Biden had been trying to turn his life around at the time of the gun purchase, having completed a detoxification and rehabilitation program at the end of August 2018.

“There is no evidence of contemporaneous drug use and a gun possession,” defense lawyer Abbe Lowell wrote in court papers filed Friday. “It was only after the gun was thrown away and the ensuing stress … that the government was able to then find the same type of evidence of his use (e.g., photos, use of drug lingo) that he relapsed with drugs.”

Hunter Biden’s daughter Naomi took the stand for the defense Friday, telling jurors about visiting her father while he was at a California rehab center weeks before he bought the gun. She told jurors that he had seemed “hopeful” and to be improving, and she told him she was proud of him. As she was dismissed from the stand, she paused to hug her dad before leaving the courtroom.

The defense on Friday did not rule out calling one more witness, but it was unclear who that could be. Hunter’s lawyers had previously said they planned to call as a witness Joe Biden’s brother, James and he was at the courthouse on Friday. Testimony from other family members could open the door for more deeply personal messages to be introduced to the jury.

President Joe Biden said last week that he would accept the jury’s verdict and has ruled out a pardon for his son. First Lady Jill Biden was in court every day last week to support Hunter, except on Thursday when she was with the president in France for D-Day anniversary events.

It looked as if Hunter Biden would have avoided prosecution in the gun case altogether, but a deal last summer with prosecutors imploded after U.S. District Judge Maryellen Noreika, who was nominated to the bench by Republican former President Donald 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 in taxes over four years.

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