Reports that Bafana Bafana captain Senzo Meyiwa's family appointed private investigators to help solve his murder put pressure on police, the Institute for Security Studies (ISS) said on Wednesday.

"I think the fact that private investigators were appointed may... put the police on their toes to do their best," ISS crime and justice department senior researcher Johan Burger said.

Meyiwa, captain and goalkeeper of the national team and Orlando Pirates, was shot dead in Vosloorus, Ekurhuleni, while visiting his girlfriend, singer and actress Kelly Khumalo, on Sunday night. The attackers apparently demanded cellphones and money.

Burger said in cases where there was national and international media interest, police would be more likely to put together special investigative teams.

"It happens in many other countries. They tend to prioritise highly publicised cases."

He said there were a number of reasons a family might choose to appoint private investigators.

"This may be a form of showing a lack of confidence in the ability of police to effectively and efficiently investigate. It could be that the family believe it could speed up the process. The family is looking for immediate answers."

Burger said the private investigators could look into rumours that the motive for Meyiwa's attack went beyond robbery.

Many private investigator companies were started by former senior police detectives.

"They are often highly skilled, highly experienced detectives, and families want the best."

The Witness reported on Wednesday that KwaZulu-Natal private investigator Shaheen Sulieman was one of those Meyiwa's family had appointed. He and his team were travelling to Johannesburg to join the police investigation.

Meyiwa's cousin Siyabonga Miya was quoted as saying that the decision to enlist the help of private investigators "was not any vote of no confidence in the police".

Earlier, Brigadier Neville Malila said two people questioned about the killing were released without charge.

"One person presented himself after we issued [identikits] of the suspects. On Facebook, he said, people said he looked like one of the pictures.

"The investigators interviewed him and he could not be linked."

A second person was brought in for questioning by metro police.

Neither could be linked to the crime and both were released.

On Tuesday, police released identity kits of two dreadlocked men with gold teeth believed to have been involved in the shooting.

A reward of up R250,000 has been offered for information leading to the arrest and conviction of the killers.