To unlock Spindler’s Search collectible achievement or trophy in Prototype 2, you need to destroy all Lairs in the game.
It isn’t that hard to spot them and you will come across them while playing through the story but, if you aren’t careful, you can easily miss them. Trick is to keep your eyes on the screen for any symbol or notification that pops up.
You will notice this symbol every time you a lair is nearby. Next step is to enter the lair and kill all the marked targets inside.
There are total 9 lairs and you can keep track of your progress through in-game collectibles map which will show you how many lairs are in each area and how many you have found. If you find it difficult to find any lair, keep flying close to streets and you should find it.
Note. To make things ultra easy, add coordinates (longitude, Latitude) into Prototype 2 map and it should lead you to the selected lair.