Edmund O'Brien
His character in this seems similar to the one he played in "The Killers", (1946), except that he's an undercover guy here rather than an insurance investigator. At the end of The Killers, he wants a vacation and his boss gives him one- until Monday, (it's Friday), and he laughs. In this film he's just completed an assignment when he enters 20 minutes in, he's looking forward to a nice vacation- and gets assigned to Cody Jarrett.
The past is a series of presents. The present is living history we are privileged to witness