Dealing with "messy" toileting. Any suggestions?

My Father, who has Alzheimer's/Dementia, makes a mess 100% of the time around the toilet. I go in afterwards and find urine on the seat, floor, base of toilet. After bm's there is feces residue on the seat, his hands, on the wall. He doesn't wear adult diapers because he does make it to the bathroom. It's when he is in there the mess happens. I'm at my wits end cleaning up after every bathroom visit. He never flushes and doesn't wash his hands. I've asked him to flush especially after a bm and he contends that he always flushes! I told him he doesn't and he said it must be someone else and not him. It's very frustrating! I keep a bottle of diluted bleach in a spray bottle and an old rag by the toilet to clean up. Everytime! Please does anyone have any suggestions? Thank you!