When you’re collecting digital evidence from an iPhone keep in mind that WhatsApp may save photos to the phone by default- any
photos any group decides to forward to the phone’s owner. So the photos on the camera roll are not necessarily ones that the user saved.
Check under settings for WhatsApp, and under Chats . . .see if the option for ‘Save to Camera Roll’ is checked off.
It’s a good idea to keep this deactivated not only to save storage space but also to avoid any confusion about where suspect photos on a cell phone came from.