My question involves criminal law for the state of: Wisconsin

A friend I know recently stole from ShopKo. They made it out of the store, but the alarm went off. When they got into their car, a citizen pulled up behind them and tailed them for a while. They assume that the citizen called the police and got the license plate number.

My friend hasn't been arrested and this all happened in one day. Does my friend have to continually worry about their freedom? How do they find out if criminal charges have been filed against them?