Keep in mind that Nash has no obligation to be completely honest in the assertions he makes in his motions.
Prosecutor Canepa knew the facts very well about how many people Jake killed and how many the Georges killed. Jake cannot lie without risking his plea agreement and Canepa has a mountain of evidence to back up Jake's claims.
Prosecutor Canepa didn't lie about how many victims Jake killed. She wasn't mistaken. Nash is the one who is either mistaken or bluffing. He's allowed to do that, the state is not.
All Nash has to do is repeat whatever lies George 4 has told him and he's safe. He knows that.
Representing a Client the Lawyer Thinks Is Guilty
Now, if someone believes a killer like George 4 over Prosecutor Canepa and a mountain of evidence and expert testimony, well they shouldn't expect everyone to agree with them.
JMO
ETA: I just re-read your post and wonder if you could clarify something for me. Are you saying that Prosecutor Canepa is lying about how many people Jake killed? Really? I hope I'm wrong. TIA
JMO
JW pled to killing 5 and I think the state and evidence plus his plea means that is the facts, his shooting one other victim may have been kept quiet by state when JW pled so that if others came forward that piece of information had to come from them, JW plea was sealed, when AW made her plea I think she confirmed JW shooting a sixth victim (JW not being the fatal shot) so it added credibility to both JW and AW story if they both revealed unbeknownst to each other the sixth shot.
I think JW shot Dana, HR, CRJr, FR, HG, I think GW the elder shot CRSr GR KR, and JW shot one of CRSr GR KR but unsure exactly which one, I would say most likely CRSr
I would also say it is unethical for state or defence attorneys to lie in open court, or mislead/lie to a court via motions, I happen to think neither side have lied in this case