The 19-year-old's intentions became known after private messages to friends and social media posts were leaked after their wedding.
One text shows the bride bragging to her friends about being “the sole person who gets his inheritance”.
Another social media post shows the teenager gloating that she is “one day closer to being widowed” by the age of 30.
It's believed the dementia patient's wife and children have all passed away, which means there's no-one left to challenge the woman's actions.
“This is heartbreaking,” said one. “I hope someone steps in and has this marriage annulled.”
Added another: “She should be in prison.”
This article originally appeared on Over60.