My mother passed away on April 4th 2021 I was her caregiver and lived with her I wrote and signed all her checks my brother is questioning sum of the

I lived with my mother and was her caregiver I wrote and signed her checks for her She had hired a man to drive her to appt as well as do odd end jobs He cashed sum checks dated before her death but cashied after her death . these checks were all approved by my mom As well as she gave him her car . my brother came into her house and took her box of important papers it had her will and car title in it . also there was 2 purchases on her credit card within two days of her death made by me and he is wanting to press charges . any thing my mother may have signed or changed about her will from 1999 was also in the box he took along with to guns . how can I prove all checks were wrote at her request ? How can I prove she had changed her will from naming him executor . he had refused any contact with her for over 1 yr. Only came to her house while she was in the hospital to remove the said property above without her consent