GDPR and photos taken during a planning enforcement investigation - Public forum - Planning Advisory Service (PAS)

It has been brought to my attention that photographs I take during an enforcement investigation may be subject to GDPR and have to be deleted if the perpetrator requests (I currently have a case where the perpetrator has requested this). This sounds like nonsense to me, but can anyone clarify if this is the case as potentially the photographs could go to court as evidence if the perpetrator is prosecuted. Many thanks