DES MOINES, Iowa — The first of two trials for a Minnesota teenager charged in the slayings of two Iowa convenience store clerks last fall is scheduled to begin Monday in Carroll County, Iowa.

Michael Richard Swanson, 18, of St. Louis Park, is charged with two counts of first-degree murder and first-degree robbery in the Nov. 15, 2010, shooting deaths of store clerks in Algona and Humboldt. If convicted in either of the slayings, Swanson would face a mandatory sentence of life in prison.

The first trial is for charges in the death of Sheila Myers, 61, who was working at a Kum & Go store in Humboldt when Swanson allegedly walked into the store about 10 p.m. and shot her after demanding cash and cigarettes. He was arrested later driving his family’s Jeep Grand Cherokee at a McDonald’s in Webster City.

The trial was moved from Humboldt County to Carroll County in western Iowa because of pre-trial publicity.

Up to 150 potential jurors will report to the courthouse in Carroll Monday.

Humboldt County Attorney Jennifer Benson said she expects a jury to be seated Monday. The trial is expected to last about a week, she said.

Benson declined further comment about the case or the start of the trial.

Swanson also is charged in the slaying of Vicky Bowman-Hall, 47, who died after being shot at the Crossroads Gas Station in Algona.

Authorities charge that Swanson shot Bowman-Hall just after 9 p.m. and then drove to Humboldt where he allegedly shot and killed Myers.

The trials were separated because they happened in different counties.

Swanson’s attorney, public defender Charles Kenville, had argued for them to be joined because of he plans to use an insanity defense in both cases. He was out of town and not available for comment.

Swanson’s trial for the Algona slaying is scheduled for July 27. It has been moved from Kossuth County to Lyon County in northwest Iowa.