Important Grief help

Is there a mod that is able to tell me the username of a player that is occasionally on the tekkit server his name is sniper with some numbers i am asking this because i am being told he griefed and stole from me 15mins to 2 hours ago and i just want to see his last logout time so i can see if there is a chance it was him thanks. he has stolen things before as i caught him in the act but let him off that time but after that things would randomly be gone from my chests now im getting annoyed