Commander Shepard is asked by C-Sec detective Chellick to pick up some mods from Jax to help him with his investigation, when the Commander asks Chellick to stop endangering Jenna who is acting as an informant in Chora's Den, and get her out of there, on behest of Rita. Chellick agrees to get Jenna out of the club but insists that he still has his investigation to complete.
Chellick tells Shepard to go to the Lower Markets and meet Jax. He cautions Shepard to be careful not to tip Jax off as he doesn't want to lose his leads. When Shepard meets Jax, the Commander can either follow through Chellick's request and hand over the payment, or try to arrest Jax, leading to a firefight, resulting in Jax's death.
If Jax is given his payment, he doesn't suspect anything and leaves quickly, unaware Chellick can still track his movements and use him to find other buyers in the future.
- Being a krogan, Jax has higher health than humanoid enemies like his bodyguards. He possesses only three bars of shielding, which will regenerate over time. His health regenerates as well and he will get back up after the first time you kill him. This revival can be prevented by using Chemical, Incendiary or High Explosive Rounds, as they will destroy his body. Killing him while he's in the air (possible with Lift, Throw or Singularity) will also do the trick.
- As he can only attack at short range, using Throw to keep him away is a good idea. Alternatively, the player can stun him with Neural Shock or simply disable the shotgun with Sabotage (the latter will leave him unable to shoot, since he doesn't carry any sidearms. However, he will still be able to attack you with Berserker Charge.)
- Unlike his bodyguards, Jax can follow you if you retreat from the Lower Markets. This allows you to kill him easily when he's unsupported and deal with the bodyguards later.