Pasadena-based Guidance Software, a developer of digital forensics and ediscovery software, announced today that it has acquired "substantially all" of the assets of Tableau, LLC, a developer and manufacturer of computer forensics hardware. Guidance said it paid $12.3M in cash for Tableau. Guidance said the acquisition would extend its leadership in the computer forensics area. The company said it expects the transaction to increase its 2010 revenue by $3M, and that the deal includes cash worth $1.6M. Tableau's software is used in computer forensics to prevent the modification of data on hard drives during the computer forensics process.