Technically you can, but you need to down the same person two or three times before they're susceptible to it, so it almost never happens (especially since you can't tell who's who as the Predator, so you can't really target the same person specifically in order to try and do it).
I also feel like that's something they should either have available from the get-go, or possibly have it that everyone who respawns back in via reinforcements can potentially be stealth killed. Right now there's basically no downside whatsoever for reinforcements, so I definitely feel like they need to nerf that in some way.