Hudson's former brother-in-law, William Balfour, is on trial for shooting her mother, brother and sister Julia's son.
The Chicago Tribune said the Oscar-winner also left the courtroom Tuesday when graphic evidence was presented during the second day of Balfour's trial.
Cook County Deputy Medical Examiner Mitra Kalelkar showed the images of Hudson's young nephew Wednesday morning, explaining how Julian King was shot twice in the head as he lay face down in the back of an SUV, the Tribune reported. The child's body was found three days later in the abandoned vehicle.
The newspaper said Hudson returned to the courtroom as a Chicago police officer testified about how Balfour's cellphone records were used to trace his whereabouts and activities in the time period the slayings took place.