How to find out if competitor is redirecting other domains to his money site?

One of my competitors with a brand new site started outranking me. The domain is 6 months old, has barely any authority, has 9 indexed pages and a total of ... 9 backlinks. The backlinks are not contextual, no PA and no PR. I just can't figure out how this guy jumped to #3 out of nowhere when I have been floating around #5 or #6 for nearly a year. This is a buyer kw with 12000 searches per month, so the competition is pretty spicy.

Is there any way to find out how he is doing it? Could he be using something like a 301 redirect or some other BH technique? And, if so, how can I find out what it is that he is doing?

Thanks!

This is the best place to start But is not free

http://www.spyfu.com/

Ahrefs will tell you how many and what redirects it has discovered.

I don't mind paying. Just signed up, seems like a very useful tool.

Thanks for the tip!