Victoria state police chief Simon Overland said a senior detective was facing dismissal over the messages, which The Age newspaper said included a graphic image of an ethnic minority man apparently being tortured.
Overland declined to elaborate on the details of the material, but said some emails were so serious that they raise "real questions about a number of individuals' suitability to continue with Victoria Police".
"The material that we're speaking about generally is of a serious nature and I think if the community were to become aware of the exact detail it would cause significant concern," Overland told public broadcaster, the ABC.
According to The Age, several police had added "sickening" comments to the torture email and would face "serious internal charges".
Victoria police are already under fire for their response to attacks on Indian students, including a murder, which prompted a cartoon in Indian media likening the force to the Ku Klux Klan.
At the time of writing, Victoria police made no mention of the investigation on their online news website.