hi terious 1st you have to check is there security logs enable from group policy if not then enable security log . then you can find in event log then security and find event id: 4740 . you fill find computer name there for step by step guide i have mentioned weblink
http://woshub.com/troubleshooting-identify-source-of-active-directory-account-lockouts/
hope answer the question if issue resolve please accept anwser and vote thanks