Private investigator, Mike Bolhuis, has revealed that he is finalising his investigation into the Joost van der Westhuizen sex tape saga.

Last week, a tabloid magazine published footage of a person it claims is the former rugby player engaging in sexual acts and snorting a white substance.

Van der Westhuizen is adamant it is not him in the footage and has hired Bolhuis to find out who is behind the video.

"Who was involved, where did it start, what was the intention would be exposed. However, we feel that the damage has already been done enormously against the van der Westhuizen family," said Bolhuis.

Meanwhile, Heat magazine said it had the footage forensically tested and it was established that the footage was not doctored in any way.