this article says D chatted with K, and Jaya chatted with actors S and actor N, so that means no direct communication between D and Jaya so why they checked D's watsapp ?? that means they are getting their lead from somewhere else too and obviously we are not seeing all the evidences........
Yesterday Arnab Or Navika(not sure) mentioned they have some other evidence as well but couldn't share those. Maybe this points in that direction.
Edited - Deepika and karishma were both part of whatsApp group with Jaya, so we can't rule out that she might have directly chatted with Jaya.