Gordon Cleveland, the gun store clerk who sold Hunter Biden the firearm at the center of the case, returned to the stand.

Cleveland was being cross-examined by the defense after testifying for the prosecution yesterday.

Hallie Biden, Hunter Biden's former romantic partner who is the widow of his brother Beau Biden, is expected to be the next witness following Cleveland.

Court resumed this morning with a sidebar conference.

Prosecutors and defense attorneys were arguing before the judge about an exhibit the defense wants to introduce when Hallie Biden, Hunter Biden's former romantic partner, takes the stand as expected later today.

Separately, defense attorney Abbe Lowell signaled his intention to file a motion to have the case thrown out after the government rests.

The long-shot bid will be filed on grounds of constitutional shortcomings and insufficient evidence, Lowell said.

Lowell also said his witnesses -- which could include President Joe Biden's brother James Biden and Hunter Biden's daughter Naomi Biden -- may not be available until Friday morning.

Hunter Biden has arrived at the Wilmington courthouse for today's proceedings.

Like previous days, he was accompanied by his wife, Melissa Cohen Biden.

The gun store clerk who sold Hunter Biden the handgun at the center of the government's case returns to the witness stand this morning on Day 4 of the trial as prosecutors look to wrap up their case against the president's son.

Prosecutors said at the end of Wednesday's proceedings that they plan to call six more witnesses -- including Hallie Biden, perhaps their most crucial witness -- before resting their case, which could happen as soon as this afternoon.

Defense counsel have leaned into their claim that Hunter Biden was not actively abusing drugs in October of 2018, the month of his gun purchase, and therefore did not knowingly lie on the federal firearm application form.

Zoe Kestan, one of Hunter Biden's ex-girlfriends, testified Wednesday that she witnessed him smoking crack the month before and the month after his gun purchase, but had "no idea" what he was doing in October.

To fill that gap, prosecutors plan to call Hallie Biden, his brother's widow with whom Hunter Biden was romantically involved.

"The evidence will show that during those 11 days, the defendant continued to use drugs and to talk about his drug use with Hallie," prosecutor Derek Hines said.

Taking the stand as a prosecution witness, Hunter Biden's ex-wife Kathleen Buhle described how, after 25 years, their marriage deteriorated under the weight of his drug and alcohol addiction.

Buhle said she first learned of Hunter Biden's crack addiction when she discovered an empty crack pipe in an ash tray on their side porch the day after their anniversary in 2015. Hunter Biden was kicked out of the Navy in 2014 for testing positive for cocaine, and Buhle said ever since then she was "worried, scared" he would abuse drugs again.

When he was on crack, Buhle testified, "He was not himself … angry, short-tempered, acting in ways he wouldn't when he was sober."

She said she would find drug "remnants in little bags" and drug paraphernalia like "a broken crack pipe" -- often enough that she would search his car before allowing her daughters to use it.

In what could be a blow to one of Abbe Lowell's lines of defense, Buhle said Hunter Biden frequently interacted with friends and family, worked, and socialized while under the influence of crack cocaine -- and would often try to hide it from those close to him.

"Did you see him, for lack of a better word, function?" prosecutor Leo Wise asked.

"Yes," Buhle confirmed.