Senior superintendent Jeremy Veary, head of Operation Slasher, told the SABC programme, Special Assignment, that the murders were similar to those committed by local gangs.
He said the house at 7 Graham Road was in an area controlled by the 28s. He said the gang saw this area as their turf and would not allow anyone else to operate there unless they paid to do so.
Captain Etienne Terblanche of the provincial police said they were baffled by Veary's remarks.
"He has no connection to the case. His theory on the involvement of the 28s is pure speculation," he said.
He said it was true that murders involving multiple victims had been committed before in the Western Cape.
"However, it was never as many as in this case. In other cases, it was simply someone who entered a place and mowed down the occupants.
"This time, the murderers had total control over the crime scene. The fact that the victims were tied up and were lying in rows before they were shot, points to something different," he said.
Police are still searching for four white men in connection with the murders. The men were seen near Sizzlers massage parlour the week before the murder. They apparently were looking for two men who used to work there.
Veary was reappointed to his post as head of Operation Slasher after he was suspended in August last year.
A disciplinary hearing found him guilty on three of 14 allegations he was facing.
Cops release name of ninth victim
He was dismissed from his post because he ignored orders from provincial police chief commissioner Lennit Max, but his dismissal was suspended for a year. He was fined and warned on the other two allegations.
Meanwhile, the ninth victim of the Sea Point massacre to be identified was Timothy Greg Boyd, 29.
The other victims were Eric Otgaar, 55, Travis Reade, 20, Fanie Fouché, 17, Warren Visser, 22, Sergio de Castro, 20, Juan Meyer, 22, Marius Meyer, 21, en Gregory Berghaus, 43. Reade was cremated in Cape Town on Wednesday.