As the government deepens its argument against Hunter Biden, prosecutors are expected to start calling his former partners to the stand on Wednesday, inviting them to air sordid details of his life and the depths of his addiction to crack cocaine.

The trial resumed at 9 a.m., with Mr. Biden’s lawyer Abbe Lowell attacking what he sees as a major weakness in the government’s case: The lack of documentary evidence, in the form of texts to drug dealers or the defendant’s written accounts, that prove he was using drugs at the precise moment he bought a gun in October 2018.

On Tuesday, prosecutors presented texts that showed Hunter Biden’s desperate scramble to obtain crack cocaine in the spring and summer of 2018. A day later, in his cross-examination, Mr. Lowell was able to get an F.B.I. agent to admit that none of the material covered his activity in the fall.

In his effort to prove that Mr. Biden lied about his drug use on a federal firearms application in 2018, the special counsel, David C. Weiss, has signaled that prosecutors will call Mr. Biden’s former wife, Kathleen Buhle, who is locked in a yearslong fight with him over alimony payments. The two divorced in 2017 after nearly a quarter-century of marriage and have three daughters.

Ms. Buhle is one of three women expected to testify about their relationships with Mr. Biden and his struggles with alcoholism and addiction. The remaining witnesses will include Hallie Biden, the widow of his brother, Beau, who is his onetime girlfriend, and Zoe Keston, who dated Mr. Biden from December 2017 to October 2018.

The presence of Mr. Biden’s family and friends, including his mother, Jill Biden, who appeared on Wednesday in a pink pantsuit, has underscored how the trial is all but certain to be a painful and personal ordeal for President Biden’s family.