Drugs, nukes and animal operatives: Project MK-Ultra, the CIA’s infamous human mind control project, wasn’t the only thing that was going on in the ‘60s.

In that decade, writes Tom Vanderbilt for Smithsonian Magazine, “the U.S. government deployed nonhuman operatives–ravens, pigeons, even cats–to spy on Cold War adversaries. “ Unlike MK-Ultra, this project was never the subject of a Congressional hearing, but some documents as well as sources from inside the CIA confirm that Project Acoustic Kitty was real.

Cats are infamously disobedient, but the CIA believed that with the right training, they could become spies. The organization also wanted to exploit another of the animal’s traits: curiosity. It thought that a cat wired to record sound would be able to come and go unnoticed, and with the use of audio cues, could be controlled to go where it would record interesting sounds–like talks between Soviet leaders.

The cruel story of Acoustic Kitty in its most basic form crops up in a number of places. As told by Victor Marchetti, who was formerly an assistant to the CIA’s director, it basically involved creating a FrankenKitty. “They slit the cat open, put batteries in him, wired him up,” Marchetti is usually quoted as saying. “They made a monstrosity.”

It sounds sort of believable. After all, the 1960s CIA was up to a lot of kooky stuff. But the story of Project Acoustic Kitty isn’t that simple, writes Matt Soniak for Mental Floss. It “actually took five years to complete,” he writes. After all, creating a high-tech cat was no small task in an era of reel-to-reel audio recording and room-sized computers. Not just that, the cats had to still look like cats–with no weird protrusions or suspicious scars. Soniak explains:

Working with outside audio equipment contractors, the CIA built a 3/4-inch-long transmitter to embed at the base of the cat’s skull. Finding a place for the microphone was difficult at first, but the ear canal turned out to be prime, and seemingly obvious, real estate. The antenna was made from fine wire and woven, all the way to the tail, through the cat’s long fur to conceal it. The batteries also gave the techies a little trouble, since the cats’ size limited them to using only the smallest batteries and restricted the amount of time the cat would be able to record.

After testing on dummies and live animals, the project was ready to move forward, and the first Acoustic Kitty was created. The problem that arose: she (or he–with the CIA redactions, it’s hard to tell) was just a normal cat with some high-tech innards, writes Soniak. As every cat owner knows, they do what they want::

Outside the lab, there was just no herding the cat. She’d wander off when she got bored, distracted or hungry. The cat’s hunger issues were addressed with another operation. The additional surgical and training expenses are estimated to have brought the total cost up to $20 million, but Acoustic Kitty was finally ready to venture into the real world.

On that first trip out, though, the cat was hit and killed by a taxi while crossing the road. It never even made it to the target. By 1967, the project was scrapped, along with the remains of Acoustic Kitty. “I’m not sure for how long after the operation the cat would have survived even if it hadn’t been run over,” Jeffrey Richelson of the NSA Archive told The Telegraph.

A heavily-redacted memo titled “Views on Trained Cats” held in the National Security Administration archive at George Washington University suggests that the project wasn’t viewed as a total failure. “Our final examination of trained cats.... for use in the… convinced us that the program would not lend itself in a practical way to our highly specialized needs,” the memo reads. However, discover that “cats can indeed be trained to move short distances” was “ in itself a remarkable scientific achievement,” the memo reads. If any further Acoustic Kitties were created, the documentation hasn’t come to light–but the advent of tiny computers and high-tech spy equipment has likely been part of the reason the project hasn’t been revisited.

And, come on: a $20 million feline radio transmitter? It could only have happened in the ‘60s.