If they purposely leave the soccer or pool or whatever, I kill them, instantly.
If they go to heal without being asked, I kill them and then listen to their whining.
One day, I want to see:
Whatever is the most powerful i7 on the market overclocked to 4.5 GHz,
Quad-SLI GT2 295 (that is, 8 GTX295 cores)
and 32 GB of DDR3 1800 Ram.
And probably, liquid nitrogen to cool it!
In this modern world, it wouldn't be very hard to figure out who killed him, it would just be by radio!
What if someone via team chat told you that he spotted the guy who killed his team mate and you rushed overthere and killed him?