Once again, someone appears to have sent envelopes stuffed with ricin to the government. The tests need to be confirmed, but two suspicious letters to the Pentagon were caught in an off-site mail screening. No one was exposed. The same person is also reported to have sent letters to Senator Ted Cruz and to the White House, though the contents of those have not been confirmed to contain ricin.

Ricin is a deadly toxin extracted from castor beans, and the directions for making it are no more than a Google search away. The process takes only a few days, and it requires equipment no more complicated than a coffee filter and chemicals you can buy in a hardware store. “It can be made in your house very easily,” says Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security.

In fact, it’s so easy that ricin mailers have not, historically, been a very competent bunch.

In 2003, two envelopes with vials of ricin were found addressed to the White House and to a Senate office. The potency of the ricin was too low to be a health risk. A decade later, three letters containing ricin were found addressed to Senator Roger Wicker, President Barack Obama, and a Mississippi judge. (The mailer turned out to be a tae kwon do instructor trying to frame an Elvis impersonator, with whom he had an online feud that began over a Mensa membership.) Weeks later, in May 2013, three more letters were found addressed to Obama, New York City Mayor Michael Bloomberg, and Bloomberg’s gun-control-advocacy group. (The mailer this time was an actress trying to frame her estranged husband.)