Thank you for the advice, i'll try that. A preators supposed to have a rather special look - at least, a Xenonaut wikipedia entry has nice picture of this creatrue. Also, i do have certain issues with stunning when it comes to androns. I tried all special grenades on them (since they are not quite organic) but, alas, with zero effect (both types of drones, at least heavy one, also immune... or i am "doint it wrong", so to speak).
If i am not mistaken, when i first researched it the page that appeared before me right after was blank. But than, when i decided to re-read Extraterrestrials entry in Xenopedia, it had a “Alien Leader Interrogation” chapter (with a nice pic in it) and a clear message to get the preator.