I just got the following two messages in my Event Updates:
Team Captured, N/A, Leon Iqbal Espionage Team has been captured by Unknown Race!
Enemy Agents captured, N/A, An espionage team from the Unknown Race has been captured while operating on our territory!
I'd forgotten about Leon's team. If memory serves, I set them up ages ago, on a colony on which I'd accidentally dug up some spoilers which were at the time gnawing on my engineers. That was a long time ago.
Should I expect to find POWs somewhere in one of my colonies? I've checked them all and I didn't see any.