While more than a few stubborn details have troubled me about the recent explosions and odd near-misses, a comment made by police in the San Diego "home lab" suicide prodded me into doing a little hard research into explosives.

Police were sent to the 8700 block of Costa Verde Boulevard after someone reported a strong odor coming from a condo about 1 p.m. Friday, SDPD Sgt. Jim Schorr said.

A man in the condo told officers everything was fine and shut the door, Schorr said. Within a couple of minutes, a gunshot was heard, prompting police to clear the building, Schorr said.

Might the smell have been related to the TATP/Mother of Satan/London bomber stuff that everyone's talking about? Sure enough, I found that according to news reports about the London bombing, there was a "funny smell":

Three passengers on the top deck escaped injury. According to some reports, they were covered in white powder, prompting speculation that it was a chemical ingredient, acetone peroxide, from the main device and the same explosive used in the bomb attacks two weeks ago.

The bus - which contained around 10 passengers - was evacuated and cordoned off amid fears that the main device might still explode.

Mr Maybanks, 38, said: "When I heard a bang my initial thought was that it sounded like a bomb. I went upstairs and there was a funny smell - I had never smelt anything like it before. There was smoke in the air.

"At the back of the bus on the floor was a black rucksack. I called the police and got everyone off the bus."

While that doesn't prove that Mr. Yasufi was cooking up TATP in San Diego, a funny smell followed by an immediate suicide might offer what the police call a "clue."

My curiosity was much aroused by this, and I've read plenty of reports of how "easy" it is to manufacture TATP, and how it's "the same explosive" as that used in the London bombings. So, I thought, let's see whether I, someone who barely passed high school chemistry, could track down the recipes on the Internet.

At the outset, I was drawn to an ethical discussion by the famous cryptographer Bruce Schneier, who discussed the ingredients in the London bombings. (The beginning quote is from a non-functional CNN link.):

The NYPD officials said investigators believe the bombers used a peroxide-based explosive called HMDT, or hexamethylene triperoxide diamine. HMDT can be made using ordinary ingredients like hydrogen peroxide (hair bleach), citric acid (a common food preservative) and heat tablets (sometimes used by the military for cooking).

HMDT degrades at room temperature, so the bombers preserved it in a way that offered an early warning sign, said Michael Sheehan, deputy commissioner of counterterrorism at the nation's largest police department.

"In the flophouse where this was built in Leeds, they had commercial grade refrigerators to keep the materials cool," Sheehan said, describing the setup as "an indicator of a problem."

Among the other details cited by Sheehan:

The bombers transported the explosives in beverage coolers tucked in the backs of two cars to the outskirts of London.

Investigators believe the three bombs that exploded in the subway were detonated by cell phones that had alarms set to 8:50 a.m.

For those of you upset that the police divulged the recipe -- citric acid, hair bleach, and food heater tablets -- the details are already out there.

Schneier is absolutely right about the manufacturing details -- for HMTD and TATP -- being readily available. They're all over the place, and frankly, at this point in time I don't think it makes any difference where they are. Our enemies not only have them, they've probably improved on them, and would probably consider a lot of the Internet recipes to be kid's stuff. (For "every little boy" who likes to play with bombs, of course...)

At one such recipe site, I noticed that both HMDT and TATP (yes, recipes for both are there, and one duplicates the Schneier-linked recipe) are best used as primary explosives.

What's a primary explosive?

There are two types of explosive devices, High Explosives which when initiated expand into their gaseous phase at a very fast rate. A low explosive however expands at a slow rate. A well known high explosive is C4 and Gunpowder a low explosive. Detonating explosives are very sensitive to heat, friction and impact, there are two types of detonating explosives; Primary and Secondary, the Primary is extremely sensitive and dangerous to handle, usually used in small quantities in detonators. The Secondary explosive is very safe to handle and is usually initiated by the primary explosive.

Because I tend to oversimplify things that are complicated, I found myself drawn to this recipe site because it reduces the TATP manufacturing process to two utterly simple paragraphs. (I won't reproduce it here, because it's childish and unnecessary, but just take my word for it.)

While there are plenty of TATP recipes, it was at the last site that something else grabbed my attention:

A very good secondary explosive can be made by mixing the AP with Ammonium Nitrate which is found in fertilizers. The fertilizer you use must contain at least 80 percent Ammonium Nitrate. Mix the pulverized Ammonium Nitrate with AP properly. You may use the following proportions depending on the purity of the Ammonium Nitrate.

1. Technically pure,dry Ammonium Nitrate:
90 % Ammonium Nitrate
10 % Acetone Peroxide

2. Quite pure (90%) Swedish N-24,26,28 DRY!!!!
85 % Ammonium Nitrate
15 % Acetone Peroxide

3. Poor quality DRY!!!!
75 % Ammonium Nitrate
25 % Acetone Peroxide

4. Poor quality ,damp but not wet.
50 % Ammonium Nitrate
50 % Acetone Peroxide

Please use this information carefully!!!!
The use of these explosives on humans are only justified in the case of war!!

Unless the reports are mistaken, Joel Hinrichs:

1) already had TATP (an extremely unstable, primary, explosive); and

2) tried unsuccessfully to purchase ammonium nitrate (a very stable, secondary explosive).

We also know that the police intended to follow through with their investigation into Hinrichs' attempted buy.

We are told that Hinrichs had a history of depression, but I've hesitated to call this a suicide because it seems so abnormal for any depressed person to use such a method.

But what about failure? If you can for a moment, just try to put yourself into the mind of someone like him, and ask how might the failure to obtain that crucial ammonium nitrate have made you feel? Devastated, I'd say. And not just because he didn't score the secondary explosive, either. The cops were onto him, and (in his mind at least) he was now a known, marked man. Seen this way, his suicide might very well be analogous to that of a TATP cook whose aromas drew the heat.

Might he have known the jig was up?

Obviously, this is speculation, but this is consistent both with the theory of suicide and with what is known about the facts. It's also consistent with doing something so incredibly reckless and stupid as sitting down on a bench and zoning out with a notoriously unstable device and contemplating your utter failure. (And also contemplating, possibly, the disapproval and disgust of the people you might have hoped to impress as a wannabe hero....)

While it still isn't known what was in the Hinrichs apartment because the warrant was sealed, it's very likely that there were bomb-making ingredients (and probably instructions), because after all, this was a death by homemade bomb.

One thing is clear about TATP. It's as unstable as the people who are attracted to it.

MORE: Via Dr. Rusty Shackleford, here's a report that the FBI refuse to confirm or deny whether the bomb was in fact TATP as previously reported, or what it was, because the warrant was sealed. Obviously, the bomb had to be made of something, and TATP being so simple to make, it's as likely a culprit as any.

While I can understand the need to keep the lid on an ongoing investigation (and thus not disclose certain details) the apparent urgency to deny that Hinrichs was a terrorist makes little sense in light of the attempted ammonium nitrate purchase.

Not that his failed purchase proves any connection to organized terrorist groups, of course.

But think about this. Ammonium nitrate is used for huge explosions, and it is the stuff demolition contractors use to cut through mountains. Timothy McVeigh used ammonium nitrate, and the official story has always been that he had no connection to terrorist groups. But has anyone ever suggested that Timothy McVeigh was not a terrorist simply because no organizational ties were found?

I'm wondering whether today they would. Seriously.

From the CNS story:

The head of the FBI investigation of a suicide bombing at an Oklahoma University football game said the investigation has yielded no information tying the bomber to terrorist activities, in spite of Internet reports to the contrary.

Except that I'm worried that this might not be a failure of common sense, so much as another indication of deception -- by a lot of people, both in media and government. If that's the case, it might help answer the question Glenn asked last night:

WHY SO LITTLE COVERAGE of the Oklahoma suicide bombing?