Where can laws for seniors be found?

There are many laws that affect seniors in the general law, not so many that are targeted directly to seniors. Same thing for people who are accused of elder abuse. This is not something to research on your own. You need to talk about your concerns (in order of preference) to a Community Legal Service, APS, the Police, or your own lawyer. Follow it up with the right people. They will usually give you information while you remain anonymous or give a false name.

There are certainly toll-free helplines which offer advice and can guide an older person through what steps to take.

Are you asking because of something that is happening to you or someone you know? Do you need help now?

It would be in your own State's statutes. The place to start to learn about it would be your State's department of Elderly Protective Services or Adult Protective Services (EPS or APS). Each State has its own department and can be found on the internet.