Ever since we learned Gabby Petito‘s family was suing the parents of Brian Laundrie, it seemed pretty open-and-shut to us.

Dedicated followers of the case figured it was blatantly obvious Chris and Roberta Laundrie knew what their son had done — and hid it to protect him. But we learned last week after the first hearing that legal experts didn’t seem to agree with that opinion.

For instance, Pace University law professor Bennett Gershman told The Sun he thought the judge “appeared to be skeptical” of the Petitos’ argument — which he felt was a “reach.” But Gabby’s parents may have more ammo than anyone realized!

Over the weekend, their attorney Patrick Reilly responded to the release of Brian’s murder confession. He blasted Steven Bertolino as having only released some of the notebook — strategically showing only some evidence to the press. Reilly claims there’s ANOTHER murder confession “that does not entirely match up this particular version.” Whoa! Almost like he wrote different drafts to see what stuck? Horrifying if true.

Related: Gabby’s Mom SLAMS ‘Mercy Killing’ Claims In Shocking Murder Confession Letter!

But even more important to the case was another letter Reilly claimed to have seen — one from Roberta Laundrie to her son. He said the letter, which was not in the notebook but was taken by police from the Laundrie home, contained “some pretty extreme things,” He didn’t say what but did say its contents — like about offering to help if he went to prison — make it clear it appears to have been written “after Gabby was killed and before Brian took his life.”

If this is true, it proves the momma knew — just what the Petitos are arguing! Need any extra proof she was trying to keep that quiet? The letter allegedly was marked “burn after you read”!

Another legal expert speaking to The Sun says this could be crucial. Neama Rahmani , former US Attorney and president of the West Coast Trial Lawyers, explained:

“The ‘burn after reading’ letter is important because it shows the Laundrie family’s [alleged] knowledge. They haven’t said anything publicly, all statements they’ve made have gone through their lawyer. This letter helps the Petitos show what the Laundries knew and when they knew it, and as they were putting statements out about looking for Gabby when they allegedly knew she was already dead. If the letter helps show that Brian’s parents knew he murdered Gabby that’s a very strong case.”

A “very strong case.” Hmm, looks like all that SVU tuition paid off after all?

Thus far the only defense against the letter Bertolino has offered regarding the letter is that the whole “burn after reading” thing was not meant to be taken seriously but was a reference to the film Burn After Reading. He told WFLA:

“I do know it’s a movie and what she wrote on the cover of a letter to Brian many months before the trip had the title of the movie on there.”

Seriously? She wrote the title of an unrelated Brad Pitt/George Clooney movie on the cover of a letter to her son. Really?! At this time of year? At this time of day? In this part of the country? Localized entirely within your kitchen?

Sorry, but where did this guy go to law school??

[Image via Gabby Petito/Instagram/Dr. Phil/YouTube.]