Mr Harper, who led Operation Rectangle – the 2008 police investigation into abuse at Haut de la Garenne and within other Jersey institutions – is due to appear before the Independent Jersey Care Inquiry for two days next week.
It is expected that he will give his evidence via video link.
The Northern Irishman came under fire for his handling of the investigation and has been criticised by former police officers in previous evidence heard by the inquiry.
Others, however, who have given evidence have supported Mr Harper and said that he did a good job.
The inquiry had been due to resume earlier this week having taken a break for Christmas, but those hearings were delayed.
