Federal prosecutors are wrapping up their gun case against Hunter Biden, with two more witnesses expected Friday in their effort to prove to jurors that the president's son lied on a mandatory gun purchase form when he said he wasn't "an unlawful user of, or addicted to" drugs.

Prosecutors were still planning to call a drug expert and an FBI chemist, capping a week that has been largely dedicated to highlighting the seriousness of his drug problem through highly personal and sometimes salacious testimony.