DES MOINES, Iowa — A Minnesota man convicted of first-degree murder in the shooting death of an Iowa convenience store clerk will be sentenced to life in prison next week.

Eighteen-year-old Michael Swanson will receive Iowa’s mandatory sentence of life in prison without parole Thursday in Webster County.

Swanson was found guilty in the Nov. 15, 2010, death of Shelia Myers at a Kum & Go store in Humboldt.

Swanson told police he shot Myers in the face at point-blank range. Defense attorneys argued that Swanson, who laughed as the jury’s verdict was read, was legally insane at the time of the shooting.

Swanson is also accused of killing another convenience store clerk and will stand trial in that case July 27 in Lyon County.