Prosecutors have rested their case against President Joe Biden's son Hunter Biden.

The defense is scheduled to present its case next.

Defense attorneys have said they could possibly wrap up their case by Monday, in which case jurors could begin deliberations as soon as Tuesday or Wednesday.

DEA special agent Joshua Romig took the stand to testify as an expert in the "coded language" used in drug trafficking.

He analyzed the language used in some of Hunter Biden's text messages, some of which appeared to be drug transactions.

First lady Jill Biden, back in the courtroom this morning, looked on as Romig testified.

Special counsel David Weiss, who brought the case against Hunter Biden, is also in court today.

Chemist Jason Brewer, testifying as an expert witness for the prosecution, told the jury that a brown leather pouch that contained Hunter Biden's gun at the time the weapon was retrieved by authorities tested positive for cocaine.

Brewer said there were "minimal amounts of white powder" on two locations on the pouch, which he combined and tested.

On cross-examination, Hunter Biden's attorney sought to raise doubts about how that white powder got there and who put it there -- emphasizing it could have been old, dating back to before Hunter Biden purchased the gun.

"You can't date when it got there?" defense attorney David Kolansky asked.

"I cannot," Brewer said.

Kolansky also emphasized that five years went by from the time the pouch was collected in October 2018 to when it was tested in October 2023 -- after the indictment in this case was already filed.

He emphasized the importance of the "chain of command," which Brewer conceded was "very important."

Earlier, Hunter Biden's former girlfriend Hallie Biden testified that she put the gun in the pouch, which she found in Hunter Biden's vehicle, after she discovered the weapon in the vehicle and before she disposed of it in a trash container.

Proceedings resumed this morning with the government calling FBI chemist Dr. Jason Brewer to the stand.

Brewer is testifying as an expert witness.

Prosecutors said they would then call a DEA officer as their final witness.

A member of the jury that found Hunter Biden guilty told ABC News after the verdict that the trial was a "waste of taxpayers' dollars."

"I just think he needs help. He needs rehab," the juror told ABC News regarding the defendant. "In my opinion, this is a waste of taxpayers' dollars. They should have fined him."

Asked what she thinks a fair sentence would be, the juror said, "I don't think that anyone who is a nonviolent drug addict should be in prison. Just fine him. We know he did something wrong. Just fine him. He needs help."

She said the jurors "worked together really well."

"Considering who his father is and the political climate in this country, it turned out better than I expected," she said. "There was no fighting in the jury room."

Judge Maryellen Noreika said before court ended that she would schedule a sentencing date in the next 120 days. Hunter Biden could face up to 25 years in prison, though legal experts believe he will not serve time as a first-time and nonviolent offender.

-ABC News' Mark Guarino