Los Angeles County District Attorney Nathan Hochman says Erik and Lyle Menendez needed to ‘fess up to all their lies when talking to TMZ from prison … but their lawyer Mark Geragos says prosecutors are focused on the wrong things.

Nathan and Mark joined us Monday on “TMZ Live” and we asked them about the upcoming resentencing hearing and the brothers’ bid for freedom.

Hochman digs his heels in and argues why Erik and Lyle should remain behind bars  … telling us the Menendez Bros missed a golden opportunity to take responsibility and apologize in their recent TMZ special.

The judge ruled in the brothers’ favor Friday and granted a resentencing hearing that could set them free … but in the Friday hearing, Hochman took some heat for showing old crime scene photos in front of Menendez family members … and now he’s apologizing.

Mark joined us later in the program and pushed back on Hochman … he says Hochman is ignoring the issue at hand here — rehabilitation.

Geragos, who cohosts our “2 Angry Men” podcast, says everyone agrees Erik and Lyle are rehabilitated.

We also tried to press Mark again on whether he’s representing Diddy in an upcoming trial … but watch, he reverts back to an old trick of his.