The phrase "deputy chief" refers to the second-in-command or assistant to the chief of an organization such as a police department or a company. They help the chief in managing and making important decisions. Full definition
Short, a former deputy chief executive of the borough council, said party membership had increased by 50 % during the campaign. (theguardian.com)
He previously served as deputy chief academic officer for Friendship, overseeing school budgets, special education and student support services. (friendshipschools.org)
Our new deputy chief spent eight months trying to get our crime laboratory closed down. (syracuse.com)