US prosecutors say they'll seek a life sentence for a suburban Chicago man accused of beating a four-year-old girl to death after she spilled juice on an Xbox video console.

The Chicago Tribune cites prosecutors as saying "heinous" circumstances justify the sentence for 19-year-old Johnathan Fair, of Waukegan, if he's convicted of first-degree murder in the death of his girlfriend's daughter, Skylar Mendez.

Lake County prosecutors say Fair was babysitting Skylar last month when she was fatally injured.

Fair brought her to a hospital and initially claimed she'd fallen. She died a few days later.

Defence lawyer Sam Amirante told The Associated Press on Sunday that he's confident his client will eventually be acquitted.

A grand jury indicted Fair on Wednesday. Prosecutors announced their intentions on sentencing on Thursday.

Fair's arraignment is set for February 17.