To outsmart tax evaders who resort to delete their financial data or hide it in password-protected devices during search operations, the I-T department has started including portable forensic labs and experts in its team.

The department has unearthed links to more than Rs 1,000 crore money in the last few searches with the help of cyber forensics, according to sources.

The search teams now visit premises of assesses equipped with pre-wiped disks for imaging and cloning hard drives, portable labs for previewing computer hard disks, evidence bags and tags to pack, label and transport the imaged and cloned data to its labs.

Taxpayers and evaders have increasingly started using high-end softwares like 'logic bomb' which deletes all files as soon as investigators try to source information from the hardware.

While password protected CDs, DVDs, pen drives, MP3 players, ipods and SIM cards are used to store and conceal the voluminous records of transactions and payments to evade taxes, the sources said.

The department clones hard drives and other hardware in the presence of the assessee and prepares a 'panchnama' with the help of forensic experts drawn from the department or hired from outside. An on-the-spot seizure of the electronic data is necessary after instances of "zero storage" happened when the seized hardware was re-opened in department's forensic labs, they said.

The I-T authorities, in a recent search conducted on a prominent food and spices manufacturer of the country, was faced with a unique problem when the assessee provided a limited number of account books to the department admitting a lower tax liability.

The cyber forensic team then went through the companies numerous hard drives and ferreted out the hidden account books resulting in disclosure of transactions to the tune of Rs 15 crore, the sources said.

The department also recovered Rs 74 crore of concealed income from an on-spot analysis of servers when searches were conducted on a popular apparel brand.