Retired policeman Piet Byleveld, who now heads a private investigations firm, has called on the close friends of murder victim Inge Lotz to get in touch with him, according to a report on Tuesday.
"I like to start at the beginning, and I wanted to see the set-up in the flat. Certain information was made available to me... I'm flippin' close to figuring out a motive," he told Beeld newspaper.
Lotz's parents asked Byleveld in March to track down the murderer of their daughter, who was found dead in her Stellenbosch flat in 2005.
"The murder investigation is moving in a certain direction. If these friends don't come forward, I'm going to expose them," said Byleveld.
Speaking at Cape Town airport after returning from a visit to the murder scene, Byleveld said he made "certain observations" at Lotz's flat.
He declined to discuss names or reveal further details, but urged Lotz's friends to contact him at firstname.lastname@example.org.
Lotz's boyfriend, Fred van der Vyver, was put on trial for her murder but was acquitted in November 2007. He is in the process of suing the State for damages for malicious prosecution.