One of the lawyers of Erik and Lyle Menendez says the handwriting is already on the wall with the new L.A. County District Attorney ... and the writing he saw wreaks of bias against the bros.

Bryan Freedman wrote a scathing email, obtained by TMZ, to new D.A. Nathan Hochman, calling him out for meeting with only one Menendez family member ... the one who has gone on the record calling the 2 men cold-blooded killers and advocating that they rot in jail.

Freedman wrote, "Nathan, as I mentioned to you the day after the election ... I represent over 20 family members of Jose and Kitty Menendez ... There is concern however that your process of gathering information from the victims has been unfair."

Then Freedman lowers the boom ... "instead of wanting to meet with the victims family members that can share their own personal experiences of years watching and speaking directly with Lyle and Erik, you chose to meet with Milton Anderson's attorney first ... It does not make any sense to my client."

Freedman goes on to cite allegations various family members have made against Anderson, but even more significantly, the lawyer says "I thought that when you were ready to meet or talk to the victims that you would want to meet or hear from the victims that knew Lyle and Erik best over the past 30 plus years of incarceration. Instead of that happening, I was very surprised to read that you had instead spoken with the attorney who represented the one family member who did not interact with Erik and Lyle over these past 30 plus years."

He went on ... "Anderson has no personal knowledge of how Lyle and Erik have behaved while incarcerated nor can he opine on whether they are a threat to society since he has not interacted with them in any way."

And with the following the war begins ... "Was it Kathy Cady (Anderson's lawyer) that you met with on behalf of Milton Anderson? If so, how was the meeting arranged with Kathy Cady? Did she support your campaign for office? Did her support of your campaign or her writing a published op-ed give Milton Anderson any advantage to be able to have his attorney meet with you?"

The new D.A. has replaced the 2 deputy D.A.s on the case ... both of whom had supported resentencing Erik and Lyle which could have led to their release.

A hearing is set for next month where Mark Geragos, another lawyer for Erik and Lyle, will not only ask for resentencing but also that the conviction be changed from murder to manslaughter based on new evidence that Jose Menendez molested his sons and errors in the second trial that led to their conviction