Peter Frederiksen, a 63-year-old gun shop owner, was arrested in the central city of Bloemfontein in September after his wife Anna Matseliso Molise told police that he assaulted her and mutilated her genitals.
Molise, 28, was set to be the state's key witness against Frederiksen before she was gunned down outside her house in Maseru, the capital of neighbouring Lesotho, a two-hour drive from Bloemfontein.
Police spokesman Brigadier Hangwani Mulaudzi confirmed Frederiksen faces charges of conspiracy to murder Matseliso, as well as three counts of assault, bigamy, and production and distribution of child pornography.
"The 'conspiracy to murder' charge was confirmed yesterday," Mulaudzi told AFP, adding that the charge related to Frederiksen's suspected links to his wife's killing.
She had told police she was drugged with laced champagne when she was mutilated.
The couple have two children together.
When police searched Frederiksen's modest townhouse in Bloemfontein, they discovered upwards of 21 frozen pieces from at least seven female genitals, as well as pornographic photographs of children, investigators have said.
Officials had identified some of his victims, which include a seven-year-old girl. Investigators also belive that some of the genitals may come from Danish women.
The Dane had previously voluntarily participated in a radio documentary for Danish public broadcaster DR in which he openly detailed performing genital mutilation on his African wife and her friends.
Police have issued an appeal for Frederiksen's alleged victims to come forward.
No one has been arrested for the murder of his wife.