Arguably, using dimethylmercury is the perfect murder weapon as it is the hardest to trace since lethal symptoms occur only after 5 months on initial contact (rapidly absorbed through the skin), giving you plenty of time to get a new passport and exit the country.

Essentially, once you obtain dimethylmercury, you gain the ability to kill anyone you don't like with near impunity. Put a few drops on their toilet seat or door handle, and you're done.

Trying to create dimethylmercury from scratch is out of the question for the average joe. If anything, they'll probably kill themselves in the process.

Surprisingly, typing "buy dimethylmercury" on Google instantly gives you a website to buy 10g 95% Dimethylmercury for $500: https://www.chemicalbook.com/Price/DIMETHYLMERCURY.htm

Lethal dose is 400mg, so 10g / 400 mg = 25 kills

For most criminals, paying $500 to kill 25 people is a pretty good deal considering it is cheaper than most guns.

There's gotta be a catch, right? It can't be this easy to obtain the perfect murder weapon.

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    If you click "buy," you get to a page saying "this product has been discontinued." Which makes sense, because trained scientists have basically stopped using it for fear of killing themselves. For the average person, any attempt to handle it would most likely result in their own death.
    – cpast
    Jan 24, 2021 at 19:27
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    Note that 'getting a new passport' good enough to pass international borders is highly non-trivial. Moving to a new country with a new identity is also nontrivial and requires serious financial resources.
    – quarague
    Jan 25, 2021 at 8:32
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    How many murderers are interested in a weapon that takes months to kill their victim? This sounds like it might be interesting in a murder mystery, but unlikely in real life.
    – Barmar
    Jan 25, 2021 at 15:42
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    @Barmar: I imagine the long period between exposure and death might be of use to, e.g. "black widows" and fratricides/matricides who are looking to inherit, or speed up the inheritance process.
    – sharur
    Jan 25, 2021 at 22:09
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    @Barmar Long-term revenge: cheated ex-lovers, cheated ex-business-partners, political long-games, everyday Russian politics, etc...
    – Dai
    Jan 26, 2021 at 1:05

4 Answers 4


There are tons of extremely complex and technical regulations governing the manufacture, sale, use, and possession of chemicals. Some lawyers spend their entire careers answering questions about them. The statutes that enact these regulatory schemes give pretty broad regulatory power to the various regulatory agencies. For example, the FDCA gives the FDA and the Attorney General broad power to regulate any "drug." And, for the purposes of the FDCA, 21 U.S.C. 321(g)(1) defines a "drug" to include any substance in the official United States Pharmacopoeia, official Homoeopathic Pharmacopoeia of the United States, or official National Formulary. These are three massive encyclopedia of chemical substances that includes almost anything you can think of. That statute is really old and was enacted when these encyclopedia weren't as massive as they are today, so there's a strong, certainly persuasive to me, argument that the original intent of the legislature wasn't to give such broad regulatory power to the FDA commissioner and the AG. But, would it carry the day before a textualist judge? The point is, the government has a ton of ways to regulate dangerous chemicals.

But I think the far, far more interesting question you raise is whether it's impossible to catch a murderer who uses this chemical. In short, I think justice could still find that killer.

The detectives are going to look for a motive, and find the people with a motive to kill. So that's going to narrow it way down. Once they've found those people, they're going to execute search warrants and subpoena the crap out of their purchase history.

Now let's say you've destroyed your computer, you made contact with the seller in person, and you paid cash. Even then, I imagine the half-life of the chemicals would allow the detectives to get a rough estimate of when the deceased was poisoned, and they could try to recreate the deceased's schedule around that time to find where she was, and who would have had access to her.

Finally, as to the point you raise about it being shocking that it might be easy to get away with murder. The sad truth is that it's not so shocking. I learned recently that clearance rate for murders by Chicago detectives is around 30%.

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    "clearance rate for murders by Chicago detectives is around 30%". But most of these aren't the premeditated, well plotted crimes that we like to read about in murder mystery novels, which are rare in real life, and which is how (CH3)2Hg is most likely to be used. Many of the 30% are domestic violence, and the obvious culprit is the wife, boyfriend, etc. And most of the 70% unsolved are crime generated. E.g. a drug dealer cheats on his supplier and is shot in the street along with 2 innocent bystanders. Police know a member of Gang X did the shooting, but have no way of knowing which member. Jan 25, 2021 at 1:43
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    @RayButterworth - Indeed. If we've learned anything from Homicide: Life on the Streets The clearance rate for "dunkers" is excellent and the clearance rate for "whodunnits" is not.
    – Richard
    Jan 25, 2021 at 9:19
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    And most of those 70% of unsolved murders aren't nearly as subtle as rare, slow-acting poisonous chemicals. They're almost entirely gunshots, with maybe the occasional stabbings. I remember when someone pointed out statistically that you actually have a better chance of winding up in prison in Chicago if you're elected mayor than if you kill someone. Jan 25, 2021 at 15:06
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    "...Dunkers are best typified by scenes at which the detective steps over the body to meet the unrepentant husband, who has not bothered to change his bloodied clothes and requires little prompting to admit that he stabbed the bitch and would do so again given the chance."
    – Richard
    Jan 25, 2021 at 19:56
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    @HashimAziz I would assume it's short for "Slam Dunk" case, a basketball metaphor implying that it's an open-and-shut, sure-thing, no real investigation needed. Jan 25, 2021 at 21:09

The case US v. Siesser is about such an attempt, where violation of 18 USC 229 was one of the charges (to which he pleaded guilty). It is a chemical weapon under the provisions of that chapter – it's not the chemical per se, it's the chemical when used for a purpose (like, killing people). Specifically

A toxic chemical and its precursors, except where intended for a purpose not prohibited under this chapter as long as the type and quantity is consistent with such a purpose.

You could buy it to calibrate NMR devices, I guess. There may be specific state regulations as well.

  • I'm surprised how they traced it back to him. I guess he was successful 2/3 times as those 2 packages weren't known to the authorities.
    – NoName
    Jan 25, 2021 at 1:24
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    Also note the motive for the case in your link: "resentment over a breakup, and a desire for the person who caused the heartache to die." You're not getting away with murder quite so easily when you kill your ex-wife.. Jan 25, 2021 at 5:18
  • Reports on US v. Siesser conspicuously avoid naming the toxin he sought, even though they name two others found in his house during a warranted search (cadmium and cadmium arsenide). Report here found an association in an affidavit with dimethyl mercury. I wonder why the U.S. attorney and the court thought the name of the toxin warranted redaction?
    – feetwet
    Jan 26, 2021 at 4:11

Purchase and possession of things well suited to serving as murder weapons is not, as a general rule, prohibited. Lots of dangerous things aren't heavily regulated.

The U.S. allows, in some circumstances, private ownership of tanks and machine guns. The classic "perfect" murder weapon is an icicle.

We live in a dangerous world, and the main legal deterrents against murder are the laws prohibiting murder or the solicitation of murder.

  • Yes but in this case it is actually difficult to trace if the item is used as a murder weapon. So we can't even hold anyone responsible after the fact.
    – NoName
    Jan 26, 2021 at 0:57
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    NoName, you also can't "trace" how someone was strangled or stabbed or anything else (if the murderer takes basic precautions). Murders are solved by figuring out who wanted to kill the victim. The method of killing isn't very important. Jan 26, 2021 at 13:55

I thought a look through the Canadian environmental act to see if a person could get mercury. According to the Products Containing Mercury Regulations (SOR/2014-254) Prohibitions

3 A person must not manufacture or import any product that contains mercury unless

(a) the product belongs to a product category set out in column 1 of the schedule, the maximum total quantity of mercury contained in the product is less than or equal to the quantity set out in column 2 and the person manufactures or imports the product on or before the end date set out in column 3; or

(b) the person holds a permit issued under subsection 5(1).

The products listed in the schedule do not contain dimethylmercury. Average Joe could apply for a permit, but that seems unlikely since the permit requires some creative story telling and a mailing address.

(c) evidence that, at the time of the application, there is no technically or economically feasible alternative to or substitute for the product that

(i) achieves a similar result as would be achieved by using the product >containing mercury, and

(ii) has a less harmful effect on the environment or on human health than the >product containing mercury;

Canada does not have any suppliers of Dimethylmercury (https://www.worldofchemicals.com/chemicals/chemical-suppliers/dimethylmercury.html). The package would need to be shipped across the border with proper labeling. Depending on your thoughts on enforcement of this sort of thing it could be a hurdle to obtaining Dimethylmercury. I understand that the criminal element would notlikely label it, but the same could be said for any weapon.

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