Sadly, theft is an issue, even in the finest of homes. My mom is at a place that is consistently rated 5 star (the highest rating given) and yet I have been frequently warned that I mustn't leave anything of value in her room. Mom use to love wearing jewelry and now I have to keep it at my house for her. She has a few rings and a necklace she keeps on, but that is it. The locked case sounds like a perfect solution, as long as your dad is lucid enough to lock it up and unlock it.
I wish you well
Fibromyalgia, Osteoarthritis, scoliosis, back problems, hypothyroidism.