“An oil spill is a crime scene,” says Christopher Reddy, but quite unlike the kind in TV whodunits, where fictional forensic whizzes help nail down perpetrators with an arsenal of lab tools. For Reddy, a chemist involved in analyzing oil spills, investigations take years, and do not always yield certain results. Reddy delivers a colorful account of his research, which includes an insider’s perspective on the Deepwater Horizon spill. He confesses that not long ago he “was thinking about getting out of the oil spill business;” the incidence of big accidents “had dropped like a rock” since 1991. Then came news of the BP well blowout. He was invited on the scene to take water samples in the spring of 2010. Reddy shows video from underwater robots collecting oil from the leaking well head, and of the fierce flames from gas burning off nearby. “You couldn’t hear anything, and you could feel the heat on your skin. I’ll never forget it,” Reddy recalls. Reddy has long experience with tracking oil in the ocean and in the diverse coastal ecosystems where it comes ashore. He has learned that even 30 years after a spill, coastal marshes and shores that appear healthy often conceal toxic sludge that wreaks havoc on flora and fauna. Contrary to oil industry claims, sites don’t rebound easily. Accounting for the Deepwater Horizon crude (nearly 200 million gallons) and its impact on the ocean and coastal environments has meant taking countless samples, and tagging them chemically. Oil is made of thousands of compounds, “each with a different personality, or behavior, like a teenager,” says Reddy, and nature treats these diverse oils in different ways: “Some evaporate, some biodegrade, or break down with sunlight.” Reddy says, “I want to know who’s (in deep water now), who used to be, and why the other guy is on the surface.” This means “punching holes in the water collecting as many data points as possible.” The result of this work, involving hundreds of surveys by Reddy and oth...