Gil is inspecting the wire Warrick cut when Ecklie comes over and gets all defensive. They do some alpha-male scuffling over evidence, and Gil demonstrates that he is clearly the superior inspector. Ecklie demonstrates that he's clearly a member of the Squamata order, suborder sauria, family viperidae. In other words, he's a snake.
So Gil goes back to Damon, who wigs out over the accelerant question and insists that there was no gasoline in the closet. See, Damon, this is what comes of lying: your credibility gets shot, and nobody believes you when you might actually be telling the truth. Gil reiterates the problem for those of us playing along at home: unless he can explain the presence of the hydrocarbon chains, the charges stand. "Then I guess I'm a dead man," Damon grits. You are, Damon. A lying dead man.
Cut to Catherine making cute with the runners outside. To make a tedious scene less so, let me describe this quickly and matter-of-factly: she and Nicky stick q-tips up everyone's noses and perform the world's fastest DNA sampling and processing. Seriously -- one minute, they're swabbing nostrils, the next, they're reading PCR results and sending everyone on their merry way. Nicky, to his moderate chagrin, loses $100 in a bet with runner 702 as to the probable innocence of the rogue's gallery of runners. There. Scene dispatched. God, this episode has been tedious. I blame Jacqueline Zambrano.
Gil is sitting at his desk, staring off into space, when Sara comes in. They talk for a few moments, and Gil reveals that this case has him at sixes and sevens. Sara proffers her theory on the case: they have melted shards of glass, on the floor of the closet, which proves that the fire burned at over 1000 degrees Fahrenheit. But between the temperature and the water, any physical traces of accelerant might have been destroyed. Ecklie drew his gasoline conclusion based on a credit card receipt, not actual physical evidence. "I can't fault him for that," Gil says, behaving a lot more fairly to Ecklie than I would.
Sara then busts out the organic chem and reminds Gil of what we all knew some fourteen paragraphs earlier: hydrocarbons are all over the place, and under the right conditions, any one of a number of household products would have combined with the short-circuit from the space heater to produce a lethal fire. Warrick confirms her science, and Gil beams -- something he should do more of -- with the realization that he's just cracked the case. He rounds up the troops for a field trip to the Damon household. "You ever worry about committing professional suicide?" Warrick asks, and Gil replies, "Not while I'm committing it, no." That Gil, he sure knows how to live in the moment.