So here you stand, beloved freak

-- Grew up as an only child with a distant mother and abusive father. Was a brilliant student but had difficulty making friends; attended Gotham City University and has a bachelor's degree in biology.
-- Worked for the GCPD as a forensic scientist up until his late twenties (see pathognomonic for the version of him from this timepoint.) Killed a police officer, Tom Dougherty, in a rage and attempted to cover up the murder but was ultimately caught and convicted. Subsequently got himself transferred to Arkham via a feigned suicide attempt and broke out. He's been living as a criminal ever since.
-- Has made a bit of a name for himself not only through elaborate heists, but also as a detective-for-hire in Gotham's underworld.