Conversation so far:
When did Theodore Roosevelt become the New York City Police commissioner?
William Lafayette Strong, a reform-minded Republican, won the 1894 mayoral election and offered Roosevelt a position on the board of the New York City Police Commissioners
What did Theodore Roosevelt do as the New York City Police Commissioner?
Theodore Roosevelt became president of the board of New York City Police commissioners and radically reformed the police force.

Question: What changes did he make to the police force?
Self-contained rewrite: What changes did Theodore Roosevelt make to the New York City Police force?