JMO, if there was anything they felt they couldn't prove, they wouldn't have allowed Jake to include it. AC and even Junk have lots of experience hearing felons lie to them. Same with Judge Deering.
GW4 is a killer, just like the rest of his family. He personally killed at least one person that night - Gary Rhoden. JMO. He may have killed more.
JMO, he doesn't deserve better treatment than the rest of his family just because he has a child. He had several months in which he could have stopped his family from murdering the Rhodens and he chose not to because he hated them and wanted them dead. He feels no remorse about their murders, he thinks they deserved what they got. Otherwise, he would be going along with Jake's plea bargain.
If there's a God in heaven, GW4 will never be allowed to see his child again. They should be left alone to rebuild their own life without the shadow of the Wagner family's horrific crimes following them into their future.
JMO