If you don't want to know the circumstances surrounding Monday's entry in this slideshow, then don't read any further...
[spoiler]Monday's quote:
Ep #111 (1966) - Vicki - 'They'll know I MUST be somewhere here on the grounds.'
From "#(0110_)0111/0112: Robservations 08/07/01: Where is Matthew?"
Think about it, Vicki tells Matthew--think what'll happen if you kill me--the sheriff will find out, come after you, and he'll capture you and you'll have to stand trial for murder. No, he says, it won't happen that way. But it will, she says--the sheriff isn't stupid, he'll know how it happened. He didn't connect me with Malloy, says Matthew. That was an accidental death, completely different, says Vicki, this is premeditated murder--so he'll be questioning, and sooner or later, they'll question you. Why me? he asks. Because they'll find out I didn't leave Collinwood--Mrs. Stoddard will tell them--they'll know I must be somewhere here on the grounds--there are only four people here--Mrs. Stodddard, Mrs. Johnson, David, and you--she points at him--(not wise, Vicki; your concept is cunning, but this man has blinders on)--and sooner or later, they're going to come up with the right answer.
[/spoiler]
This Robservations references the quote perfectly...
And, oh, the early days, when Vicki had a mind...
Not to mention her logic is sound because this is the second quote from this this ep and the first, which was back on June 6th, was: Frank - 'That means she MUST be here on the grounds. She MUST be someplace close by, but where?'