Baton Rouge’s African American history museum was found vandalized on Monday — exactly one month after it’s 75-year-old founder, Sadie Roberts-Joseph, was murdered.

Police were investigating the damage, including shattered windows and benches that were flipped over at the Louisiana institution, The Advocate reported.

Images posted on Facebook also show a wrecked outdoor garden and chairs and other furniture pushed over or broken.

It’s unclear when exactly the Odell S. Williams African-American Museum, which is closed on Mondays, was trashed.

The institution’s founder was also a community activist who reamed up with local cops in anti-violence initiatives.

She was found suffocated in the trunk of her car last month.

One of her tenants, 38-year-old sex offender Ronn Jermaine Bell, who owed Roberts-Joseph about $1,200 in unpaid rent, was arrested for her murder.