The Police and Prisons Civil Rights Union (Popcru) has also urged decisive action, saying Kinnear had applied for protection - an application which was not approved.
"Kinnear ... served the law enforcement fraternity with diligence and commitment for a time spanning over 30 years. It is understood that he was working on several high-profile investigations ... When there was an application for his protection, the application was disapproved, which begs the question as to why such a person working on high-profile cases would be left vulnerable," the organisation said in a statement.
Popcru said police killings were "cowardly acts to deviate law enforcement officials from pursuing certain high-profile cases", adding that heftier measures for those found guilty should be imposed.
"[We] urge the SAPS management to protect their own, especially at times when they [are handling] high-profile cases, which has the potential to put their livelihoods at risk," the organisation said.
Fritz also called for more police resources, including Crime Intelligence, detectives and public order police, to be allocated to the Western Cape to tackle crime, gangsterism and unrest.