Sandi, as Cary called her, was a secret to most of the principal players in Cary’s life. Yes, she was his lover (and lovers often quarrel and sometimes even do unthinkable damage to the relationship), but there was no sign of trouble between them. She doesn’t appear to have an alibi, but remember the sealed note from Thursday, March 30, left in Cary’s desk? It said he couldn’t meet Sandi on Friday as planned. But she never got that note—he forgot to get a stamp and mail it to her. That means the Friday he disappeared—or was murdered, actually—she was home all evening waiting for him. Hmmm, this is a case of a dead man providing an alibi for a woman after not sending her an important letter because he didn’t have any stamps and couldn’t ask his secretary.