Twenty-eight female guards were unfairly dismissed by a security company because the client‚ Metrora.
The sentencing of Thabo Mokhele, the so-called "Beast of Benoni", has been postponed until June 12.
Mokhele, 31, who is from Daveyton, was convicted in September of the culpable homicide of his mistress, and of the attempted murder of his wife and her friend.
He was accused of shooting his wife 12 times, wounding her friend and, while on bail, beating his mistress to death.
On March 5 last year Mokhele shot his wife, Precious Mathabo Eland, after accusing her of infidelity. She survived. Though Mokhele admitted to shooting her once, the state failed to prove he intended to murder her.
Mokhele was also convicted of trying to murder Eland's friend, Charlie Qhekung.
Two weeks later, while on bail, Mokhele accosted his mistress, Mabel Kobe, at her home in Daveyton. He accused her of infidelity and beat her so badly that she died of her injuries.