This character has gone "Psycho" long before he says, "She might have fooled me, but she didn't fool my mother"
He has, but the lie goes much deeper than the detective... [DOC] [TLE] Psycho (1960) - Greatest Films [PAR] When he leans down to peer at Marion through the hole, his eye, in profile view, 
is ... and prepares to take a shower before retiring - a final soul-cleansing act.