Chad Isaak is appealing his murder conviction to the state Supreme Court, according to documents filed Thursday.

The notice of appeal lists the preliminary reason as to whether there was sufficient evidence to support the conviction.

Isaak was convicted in August 2021 of murdering four people at RJR Maintenance and Management in Mandan on April 1, 2019. He was also found guilty of burglary for unlawfully entering the RJR building while it was closed to the public, guilty of unlawful entry into William Cobb’s RJR vehicle and unauthorized use of the RJR vehicle, which was driven to Indigo Signs shortly after the killings at RJR.

Last month, Isaak was sentenced to life in prison without the possibility of parole.

KX News reached out to the attorney representing Isaak on his appeal for comment.