What's the deal with company not paying final paycheck?

I'm dealing with a situation in Arizona and need some guidance.

company not paying final paycheck. I've been dealing with this for about 15 weeks now and the situation isn't improving.

I have worked at this company for 11 years. My position is non-exempt and I do have a written employment agreement beyond the standard offer letter.

Do I have a strong case? What should my next steps be?