Katoyi was shot dead when he and a colleague were ambushed after attending to an assault complaint in Site C in Khayelitsha early this month.
Police spokesperson Novela Potelwa said a team of detectives comprising the Hawks arrested the 32-year-old suspect on Friday. They were still in pursuit of more suspects.
Katoyi’s family commended the police and hoped that more suspects would be arrested in due course.
The family’s spokesperson, Monwabisi Jobela, said: “It is good news that someone was arrested.
"This shows that they have been working around the clock tirelessly to make sure that justice is served for Ncedo and the family.
“Even though attending the court case will not bring Ncedo back, we want to see the suspect when the matter goes to trial and hear what was the motive behind the murder,” said Jobela.
He said they would only get closure once all the suspects had been convicted.
Katoyi, 39, and his partner Mandilakhe Mangxola were on their way back to the police vehicle when they came under attack from six unknown suspects.
The suspects took Katoyi’s service pistol.
Anyone with information is requested to contact Crime Stop anonymously on 08600 10 111 or SMS Crime Line on 32211.