Family Thief

My dad and I share a home office (lockable) at his house. We both keep emergency cash handy in an envelope ranging from $2k-$3k. I know this is a bit risky but we’re a bit old school, and we are a close knit family. We were both stolen our cash on separate occasions and could only suspect without proof. Only dad and I have a key since my mom lost hers a few months ago. I have since installed a hidden camera and left a $100 bait in my drawer. I caught the intruder on video and it turned out to be my sister’s fiancée. In the video, he clearly shuffles through both drawers but does not take the bait I have left. I can also see that he used a key to enter, which is likely my moms “lost” key. I believe to have all the proof I need to accuse him as the thief, but since I don’t have proof of the actual instances or cash amounts, would my case hold up in a court? This guy is a rookie cop btw (different jurisdiction).

Knowing if I have a solid case in court against him will determine how I will approach the situation.