Correctional Services spokesman Manelisi Wolela has denied allegations that student leader Mcebo Dla.
A new police officer has been assigned to investigate the case of assassinated Atteridgeville, Pretoria, taxi boss Hosia Shime Sithole, 60.
Sithole died in a hail of bullets from an AK-47 assault rifle while sitting in his luxury German car with a colleague in a drive-by shooting on June 23 last year.
The getaway car was found abandoned in the township the next day.
Nobody has been arrested for the murder. His ex-wife was initially taken in for questioning but was released later.
The new investigator, Inspector Phillip Kgomosotho, replaced Inspector David Shibambo a month ago after members of the Sithole family complained about a lack of progress in the investigation.
Pretoria police spokesman Captain Thomas Mufamadi confirmed that investigations were continuing and said the new investigator was visiting all witnesses to take fresh statements.
In a letter written to Gauteng Police Commissioner Perumal Naidoo last year, the family complained about the manner in which Shibambo had handled the case.
They claimed that statements from crucial witnesses were missing from the docket and that fingerprints were not taken from the car used in the murder.
The family also claimed that police had passed vital information obtained from witnesses to suspects.