Step 1: Navigate to: Step 2: Open ROGame.ini in a text editor ( Notepad / Wordpad / Notepad++ )
Step 3: Search for the line: Step 4: This is the default lifetime of corpses. Setting FXLifetimeMultiplier to 2.0 will make corpses last for twice as long. To have corpses last for 10x as long, change the line to:

Note: Expect a significant framerate drop as bodies pile up! This change can dramatically affect performance. A high-performance machine can be quickly reduced to unplayable framerates as bodies pile up.

Step 5: Save your changes to ROGame.ini, and play the game!

There are other tweaks that can be made in ROGame.ini to enhance realism, at the cost of performance:

Are there any advantages?
Realism - battlefields should be littered with bodies. The advantage is you can see more long-term patterns of where players have been killed as the match progresses.

Are there any disadvantages?
It can be disadvantageous because enemies can be more easily obscured in a pile of bodies that only you can see.

Will other players see the bodies pile up?
No. Like any graphics setting, this is a local change to what you see.

Can I make weapons stay on the ground longer, too?
No.

Help! I made the changes and nothing happened!
Make sure you saved your changes and followed the guide steps. Try restoring your backup file and trying again. If it still doesn't work for you, search the guide comments for someone with the same problem. After exhausting all ideas, feel free to post in the guide comments.

What the heck is that?
Some things in war are too unspeakable to describe. In this case, only Tripwire Interactive knows why dead bodies sometimes turn into a mangled mess.