has done some pretty good commentary on the topic.  I have found his writing, and the referenced to sources, to be of interest.

Re FTC: I'm not sure why you dismiss the FTC report. I could imagine someone might claim that the FTC report was biased or unduly influenced. But the Congress has its chance to find some evidence, and so far none has been forthcoming.

In sum, demand for oil has continued to rise, snd production of oil has slowed, and some suggest it may have peaked and be in decline.

Re Katrina: the fact that prices fluctuate in response to market developments (actual or just feared supply interruptions) does not provide evidence of price manipulation.

The price for a barrel of oil and a gallon of gas in set in a competitive market. (In the old days, the Texas Railroad Commission effectively set the price of oil, but no longer.)

Prices can also fluctuate when there is little change in apparent fundamanetals, other than people's optimism or fear.  Such fluctuations may be evidence of irrationality, or fear or greed, but they are not evidence of manipulation by sellers.