You only get a crime stat if you return to an UGF after ANY mission is complete, OR you have missions (and die) in pirate-controlled facilities. (These bastards have allies that reported your trespass.)

Technique to consider:

Loot a P4-AR. Remove the Scion Compensator 2. Install a purchased (sometimes lootable) Tacit Suppresor2; install. Use looted ammo.

Loot a C54 SMG. Install a Delta x1 (Reflex). Use looted ammo.

Use the P4-AR and looted ammunition to reduce the hostile population to 3 or 4. They do not seem to acknowledge your presence (assume 20 meters away) with the silencer. You use less than one 30-round magazine for this phase. For a three-wave fight you need - three magazines.

In 3.17, guards seem to be all dead by the time phase one is complete. I also noted that the guards do not respawn during any of the follow-on waves ( on the higher missions.)

Use the C54 for the last 3 or 4 hostiles. (Alternatively, you can switch Tacit and Scion instead of using the C54 - but where is the fun in that.) They come looking for you after the first engagement and it speeds up mission completion - unless they are stuck against the wall or stuck in the spawn closet. You use less than one 50-round magazine to finish. In a three-wave fight you need - three magazines.

Loot ammo for your chosen weapons - it's free and abundant. Loot and wear guard armor of your choice; unless you are a pirate/criminal - then wear sea green. Found players encountered in UGF do not shoot guard colors (you) out of hand but will shoot hostile colors even when the target has a BIG YELLOW BACKPACK on their kit.