Alleged killer-cop cop-killer Christopher Jordan Dorner is almost positively dead, San Bernardino Sheriff John McMahon told reporters at a press conference late yesterday.

"We believe that this investigation is over," McMahon said, qualifying that officials "cannot absolutely, positively confirm it was him." Officials could not "absolutely, positively confirm it was" the rogue ex-cop because the Big Bear Lake cabin where Dorner was allegedly hiding burst into flames during Tuesday's shootout, leaving the body inside charred beyond recognition.

But how did the fire first start? There has been circumstantial speculation, based in part of police radio chatter, that the police set the fire deliberately. "We did not intentionally burn down that cabin to get Mr. Dorner out," McMahon said.

However, the sheriff did say that his deputies had shot pyrotechnic tear gas into Dorner's cabin during the standoff. Conveniently, pyrotechnic tear gas generates heat, causes explosions, and easily ignites fires. As Slate clarified in 1999:

Pyrotechnic tear gas has tactical advantages. First, the smoke cloud obscures the movement of agents as they approach a building or crowd. Second, because the metal casing becomes quite hot, it is difficult for the device to be thrown back at police (a common problem with powder grenades). The disadvantage is that it can start a fire.

The advantage to this disadvantage is a plausible deniability: Law enforcement officials can launch incendiary canisters at a target—like, say, a lakeside cabin where a confessed cop killer with a loony manifesto and a police vendetta is hunkered down—and still claim they didn't "intentionally" set the hideaway into a fiery blaze.

But it's not as if scorching the living fuck out of Dorner's lair was a magical surprise or a freak accident. That pyrotechnic tear gas could start a fire is a likely enough scenario that FBI officials spent six years vehemently denying that agents had used the military-grade weapon in the 1993 attack on David Koresh's compound in Waco, Texas, even though canisters were discovered in the rubble. In fact, Janet Reno had specifically ordered federal operatives not to use pyrotechnic devices and the bureau's eventual admission, in 1999, that it had was what sparked a 10-month internal investigation into the federal response to the siege.

The wrinkle here with the San Bernardino Sheriff's claim that his department "did not intentionally burn down that cabin" is that police voices were heard on Tuesday, in more than one instance, yelling about plans to "burn the motherfucker out." On police radio communications picked up via scanner by reporter Max Blumenthal, San Bernadino Sheriff's official can be clearly heard saying, "We're gonna go forward with the plan, with with the burn. Like we talked about." Later, a voice says, "burners deployed and we have a fire." The voice does not sound surprised or alarmed about the fire.

The verb "burn," in tactical-police lingo, may very well be shorthand for launching tear-gas canisters. (The Guardian, noting that one brand of pyrotechnic tear gas is sold under the name "BurnSafe," suggests that it indeed is.) It happens to be the same verb—and the same canister—one would use for arson.

What if the California cops did use "burn" in the latter sense, and intentionally set fire to the cabin. That would not be legal, right? You can't just go around incinerating suspected bad guys, right?

Absolutely not. "You don't blow up something either by explosives or by fire in order to apprehend somebody," said James A. Cohen, a Fordham University law professor who closely followed ther Dorner situation Tuesday. "It's the very definition of ‘excessive force' and the police aren't able to use excessive force in the execution of their duties."

So why, with Dorner surrounded, and with no certainty about whether or not someone else was inside, didn't the cops just wait him out? "Waiting him out is an increasingly risky proposition because of the possibility of escape," Cohen said. "If he makes a run for it, so to speak, he's already expressed the intention to take down as many police officers as he can. Even if it's not an attempt to escape, it could be an attempt to commit suicide-by-cop."

Besides, what would be the tangible negative consequences of burning down the cabin, assuming they could confirm Dorner was alone? Realistically, just a couple hundred thousand dollars.

"Let's assume [Dorner] has survivors," Cohen said. "Or he has a mother who says, ‘You used excessive force against my son and you killed him' and files a lawsuit." Such a suit's viability would naturally depend on evidence: no evidence, the case doesn't go anywhere; even a shred of proof would almost positively lead to a settlement. Cohen can't imagine more than low six figures being at stake. "The police see this as, ‘We took a dangerous killer off the street who said he was going to keep killing and it cost us $250,000. That's chump change to save lives.'"

Such reasoning, even in a hypothetical situation, is a slippery slope. "We have good cause to be concerned about the inattentiveness of the importance of the rule of law," Cohen said, regarding situations like the Dorner stakeout. "But we may never know—because who's going to admit to it?"

[CNN, photo by AP]