If abuse is an issue, why not hash the IP with a nonce?
For example, if you are talking with Alice and she says that she heard from Bob chat Charlie was in the office at a weird hour on the day in question investigators have gains nothing that they can admit as evidence [0]. However, there is nothing that anyone (defense or a third party) can do challenge this portion of the investigation other then keep it out of evidence, and the investigators are free to follow up with either Bob or Charlie to get something that would be admissible.