Investigators arrested Charles Alton Grinnall on June 6 after they say he held a former girlfriend hostage in a northeast Guilford County home. They say he fired several shots during the standoff, including one bullet that struck a Guilford County deputy's cruiser. Investigators say it appeared Grinnall was trying to force the deputies to shoot him. News 14 Carolina has also learned that he's undergoing a mental evaluation. Grinnall will appear in superior court Aug. 18 for an administrative hearing.