Montana's governor has signed an executive order freeing up more resources for law enforcement officers as they search for a former U.S. soldier suspected in a deadly shooting at a Montana bar last week.

The mental health of suspected Montana gunman Michael Paul Brown, 45, declined significantly following the death of his mother, relatives said.

Officers are "unrelenting in their pursuit, working around the clock" to find him, Montana Gov. Greg Gianforte stressed at a news conference on Tuesday. "Rest assured, our brave men and women of law enforcement aren’t giving up."