Police are expected to conduct DNA tests and an autopsy on an unidentified body discovered in Lingelethu West, Khayelitsha, on Monday.
They would not confirm it was Mrwetyana, a first-year film and media studies student who was last seen last Saturday leaving her off-campus residence, Roscommon House in Claremont.
Brigadier Novela Potelwa said on Saturday detectives had pursued several leads, culminating in the arrest on Friday.
“The team arrested a 42-year-old suspect in Claremont. An extensive investigation is under way to determine the whereabouts of the missing person,” Potelwa said, adding police were confident interviewing the suspect would lead to the finalisation of the investigation.