Leo Crockwell says authorities have miscalculated his prison sentence, and he should have been released from incarceration this past August. 

Crockwell, 58, was involved in a week-long standoff with police at his mother's house in Bay Bulls in December 2010. 

In February 2013, he was sentenced for weapons and assault charges. 

Justice officials, however, said Crockwell should not be released from prison until May 2014. 

A hearing on the matter has been scheduled for Dec. 19.