What to know about Hunter Biden's criminal trial Hunter Biden, President Joe Biden's only surviving son, faces three charges tied to the possession of a gun while using narcotics and has pleaded not guilty. FBI agent Erika Jensen, a witness for special counsel David Weiss' team, continued her testimony today at the trial. Hunter Biden's ex-wife, Kathleen Buhle, took the stand after Jensen, followed by his ex-girlfriend Zoe Kestan. Both of his former partners testified about his substance abuse, although Buhle said she never saw him doing drugs. The jury also heard from Gordon Cleveland, the man who sold Hunter Biden the gun at the heart of the case. Defense lawyer Abbe Lowell has tried to portray Cleveland as willing to cut corners to make a big sale.