-Corpses no more disappear (this not change that enemies killed with special ammo for example incendiary will dissolve ).
-Corpses have enabled physics (they reacts to gunfire ). This is working on enemies killed by you and your squadmates.

There is also version with only physics on dead bodies turned on. Corpses stay maybe may exceed RAM limit of this game if you have heavily modified game (Mass Effect 1 is 32bit application so it can use max 2 or 4gb ram and when there is exceed of that the game will crash ).
 
bugs for corpse version:
-bodies will disappear after load/save or loading new area
-some bodies may disappear after some cutscenes
-in rare situations game can crash at the Virmire mission before boss fight. In this situation you may want use backup file. 
If you don't have backup you probably can use it from: <game_installation>\Mass Effect\BioGame\Config - copy DefaultGame.ini and change it name to BIOGame.ini 

INSTALLATION
Choose version (corpses stay+physics or physics only ) and unpack and move file to C:\Users\<user_name>\Documents\BioWare\Mass Effect\Config and click yes to override it when prompt. Before that I suggest you make backup - in that folder you find BIOGame.ini and copy it to another folder.

UNINSTALL:
Move your BIOGame.ini from backup to C:\Users\<user_name>\Documents\BioWare\Mass Effect\Config and click yes to override it when prompt.

ACKNOWLEDGEMENTS / CREDITS
Kudos for all folks who first found and share what commands and values in Coalesced files do specific things.
Honorable mentions: corpses stay based on information in pcgamingwiki tutorial