Sean “Diddy” Combs’s sex trafficking trial starts with opening statements in a high-profile case that will not be publicly broadcast. Here are the key players.

Cassie, noticeably pregnant on the witness stand, was emotional from the start, taking deep breaths and sometimes pausing as she spoke.

The R&B singer Cassie could testify as soon as Tuesday in Sean “Diddy” Combs’ sex trafficking trial, as the Bad Boy Records founder faces charges that he orchestrated a deviant empire of exploitation that forced women into drugged-up sex parties called “freak-offs.