Let's say A="Knox killed Kercher", B="Kercher has been killed and Knoxed lived in Italy and is an intelligent 20-year-old female college student with no criminal history", C="evidence against Guede", D="Knox and Kercher were roommates", E="evidence of a staged burglary", F="bra and clasp", G="all other information about the case".

I'll redefine slightly:

• A := "Knox killed Kercher, given background info about both, but not the fact of their acquaintance". P(A) = tiny.

• B := "Kercher killed". P(A|B) = approximately P(A). (We are not yet given that they were roommates.)

• C := "evidence against Guede". P(A|B&C) = approximately P(A). (No significant connection between Guede and Knox.)

• D := "Knox and Kercher were roommates". P(A|B&C&D) = slightly higher than P(A), but still well below the threshold of consideration.

• E := "Facts cited as evidence of staged burglary". P(A|B&C&D&E) = approximately P(A|B&C&D). (Likelihood ratios involved are close to unity; certainly small relative to P(~A)/P(A).)

• F := "bra clasp and knife". P(A|B&C&D&E&F) = possibly as much as an order of magnitude higher than P(A|B&C&D). (Explaining results is a minor puzzle.)

• G := "all other information". P(A|B&C&D&E&F&G) = approximately P(A|B&C&D&E&F). (Other evidence weak; slightly inculpatory facts canceled out by slightly exculpatory facts.)