"Culpable homicide" has been defined (in South African law) simply as "the unlawful negligent killing of a human being".
Clearly OP can be correctly described as a killer and this will remain until the SCA reaches their decision in the appeal.
https://en.wikipedia.org/wiki/Culpable_homicide
Culpable homicide, like murderI is a form of unlawful killing. The crucial difference, however, is that if a person kills intentionally it is murder, whereas if he or she kills negligently it is culpable homicide.
http://www.legalcity.net/Index.cfm?fuseaction=RIGHTS.article&ArticleID=4191473
Should the SCA find him guilty of either DD or DE he can then correctly be described as a murderer.
On a different note:
OPs family has repeatedly denied he gets preferential treatment in prison. If thats the case Id really like to know which other inmates have had the benefit of the following entitlements:
He complained that he wanted a bath. Correctional Services built a bath in his cell.
He complained about his bed so Correctional Services replaced his bed.
He complained about his gym equipment so they changed that too.
He has his own cell and separate toilet
away from the general prison population.
The above comments were from Murasiet Mentoor, the regional manager of the Judicial Inspectorate who reviews written prisoners complaints.
https://www.tvnz.co.nz/one-news/world/pistorius-changes-from-angry-to-able-laugh-in-prison-q06632
And the family:
Aimee dismissed reports that prison regulations were flouted and that her brother was receiving preferential treatment.
The Sunday Times also reported that prison officials drove both Aimee and Carl's cars into the prison grounds without searching them.
Aimee "didn't comment on claims that her car was driven into the facility by a prison official and not searched".
http://www.enca.com/south-africa/bi...ceive-special-treatment-says-his-sister-aimee