Joe Marshall is a guard under the employment of Battle Tested Security, the word's most forceful military contractor run by William Rand. Marshall led the security isolating and threatening Cori Green for three days straight to not report being gang-raped by four employees while she was stationed at Basra, Iraq. For his crimes, Rand promoted Marshall to senior VP.
When Rand was kidnapped and raped by Cori's father, Special Ops soldier Donald O'Keefe, out of revenge, Joe was questioned in the presence of company attorney Virginia Pell. Marshall just smugly listed lie after lie, slut-shamed Cori, and alleged she had a bad breakup, but was like other women wanting a rush from the violence of the war. Marshall ended with no one would turn on the company except any and all washouts they'd discredit out of loyalty, before Pell walked him out of questioning.
Marshall was part of the harassment campaign against the police, while Rand also arranged the attempts on the lives of Cori and O'Keefe, successfully killing Marshall's former subordinate George Coleman when he was planning to testify. But Marshall was near being executed as well, being played a recording of Rand and Pall planning to kill him and his wife and daughters. Marshall was horrified and, after believing the tap, testified to the grand jury and lead detectives to the buried evidence of the gang-rape in a storage facility.
After Rand and Pell were arrested, Marshall likely was convicted on pleas and imprisoned accordingly. (SVU: "Official Story")