ST. LOUIS (AP) — Missouri’s attorney general is taking Walgreen Co. back to court, alleging the nation’s biggest pharmacy chain is violating a settlement reached last year over its pricing practices.

Attorney General Chris Koster’s office on Tuesday asked a judge to hold the Chicago-based retailer in contempt for violating terms of the 2014 deal.

Koster sued Walgreen in 2013, accusing it of overcharging customers and using deceptive advertising and pricing schemes in Missouri. Koster says the undercover investigation began after consumers complained that display prices didn’t match up with what they paid at checkout.

But Koster now alleges that Walgreen violated the settlement by not removing expired sales tags from shelves, and deceiving customers about those products’ prices, in roughly 1,300 recent instances.

The company said it may publicly comment later Tuesday.