I have "free electricity" and would like to mine bitcoins.

Free electricity helps, but you'll still need to invest some serious $$. Go to http://mining.thegenesisblock.com/ to calculate your return with various hardware - with a $0 electric cost, with the assumptions made, you'll never turn a profit. (Keeping in mind that most of the hardware there isn't shipping today, and some of the companies have very shoddy reputations for getting products shipped out, your return will go down, as the difficulty rate will likely have increased by the time you start mining)

With the proliferation of ASICs over the last 6 months, the mining difficulty rate has shot up exponentially.

http://bitcoin.sipa.be/

I picked up a $30 Sapphire miner about a month ago. It's one of the better hashes-per-watt miners available. At this point, breakeven for the hardware cost is about 4 months out. And that's only going to get worse as the difficulty increases, which has been happening every 2 weeks or so.

Define "free". I hope you're not doing anything that might be considered illegal or unethical.

Ordinarily, late 2013 would be too late to seriously get into mining, but if you do actually somehow have access to free electricity, that changes the equation a bit.

It's probably worth your time to look into it seriously. There are various bitcoin mining calculators you can look into online that can give you a rough idea of how long it would take to break even.

You will not make a profit unless you have an enormous amount of capital, or a new way of mining. Difficulty is growing at too high of a rate.

Stolen electricity = stolen BTC

Why not just cut out the middle man and embezzle funds straight out of their bank account?

A fee "anything" makes a lot of things worth your time... Think of recharging Teslas, for example :)

If you invest in a good and big mining ring, yes. But after that, all depend of the change rates of bitcoin…