“Well,” said Fence. “Confusion now hath made his masterpiece. Say you still that Randolph’s hand is in this?”
“I don’t see how he could have done it, Fence,” said Ted, truthfully enough. “I was watching him every minute.”
Chapter 4, The Hidden Land
Fence here echoes Macduff utterly verbatim and in similar circumstances, Macbeth Act II, Scene iii:
MACDUFF
O horror, horror, horror! Tongue nor heart
Cannot conceive nor name thee!
MACBETH LENNOX
What's the matter.
MACDUFF
Confusion now hath made his masterpiece!
Most sacrilegious murder hath broke ope
The Lord's anointed temple, and stole thence
The life o' the building!
Macduff is telling Macbeth that the king has been killed, killer unknown. Fence has just listened to enough details of the king's death to see that there is no clear culprit and the killer remains unknown. Both are essentially declaring it a mystery.