Barty Crouch is on his way to help Dolohov with a more complicated tracking ritual. The single person rituals he tried earlier in the day failed. He was startled by this. The case was designed to be tracked by those specific spells, so something is interfering.

Hydra, could you stop by or write to myself or Dolohov with the information about Padma and Dean. If this ritual fails, maybe they can track Dean himself.

Could someone in Gryffindor snatch something of Dean's with his essence on it, appropriate for a tracking spell and bring it down?

If he's been alone with that book all day, he's