ALGONA, Iowa  — A Minnesota teenager charged with killing two convenience store clerks in northern Iowa has pleaded not guilty to charges in one of the two counties where he’s accused of committing the crimes.

Online court records show 17-year-old Michael Swanson, of St. Louis Park, Minn., entered a written plea of not guilty on Thursday to charges of first-degree murder and first-degree robbery in Kossuth County. He faces the same charges in Humboldt County.

The Des Moines Register says Swanson’s attorney, Charles Kenville, declined to comment on why Swanson pleaded not guilty on Thursday. His arraignment had been set for Monday.

Kenville told the newspaper that Swanson also will plead not guilty to the charges in Kossuth County, where his arraignment is set for Dec. 28.