The article says she was living with her current husband as a common law marriage while legally married to the man who is now her ex, as if that made everything okay.
Does that mean she was just shacking up, or did she commit common law bigamy?
Well, there's no common law marriage in MN. There's no record of her divorcing her first husband/brother. But there is records of her filing tax returns with husband #2(ish) as "Married Filing Jointly" while still legally married brother/husband #1.
There is and continues be a hand-waveum attempts to explain it away as saying the necessary steps were done "In Her Faith", but once you get the state involved with marriage licenses and such, the you have to go to court and do the divorce thing to get it undone. That has not been done.
It will be interesting to see how the IRS responds, as this is generally considered Tax Fraud, as opposed to mere Tax Evasion.