Possible Clues:

• In seconds, forget about people slain with daggers
• Daggers
• After zero, mostly call into question critical marks
• 'No' -- abbreviation for 'number' -- left round marks
• Old book marks popping up in Vile Bodies
• Who believes in hiding dagger signs?
• Marks on script made by old boy, a priest
• 'Divided by' symbols (BE OIL anagram)
• At end of old book priest found signs of suspect text
• Looking up footnote markers in 'Vile Bodies'?