Brian Laundrie's Family Lawyer Says Brian Was Upset and Dad Couldn't Stop Him

Brian Laundrie was extremely upset when he left home for good about a month ago and his dad tried but failed to stop him ... so says the family's lawyer.

Steven Bertolino said on MSNBC Thursday Brian's father, Chris, tried to stop Laundrie from leaving the day he took off for the woods, but Brian was determined and there was nothing his dad could do.

The most interesting part of the conversation ... whether Laundrie's parents will reach out to the Petito family ... presumably to offer condolences and discuss what happened.

Bertolino hedged, saying certain conversations must happen first before there's any communication between the two families. He never amplified on the nature of those conversations, but he offered a hint ... that Bertolino needed first to have a discussion with the Petito family attorney.

This sounds like Bertolino is worried about a wrongful death lawsuit, which is definitely in the cards. The other fairly obvious concern ... whether cops have Brian's parents under a microscope to determine if they in any way helped him escape ... something Bertolino has dismissed as hogwash.

As we reported ... the remains found Wednesday at the Carlton Reserve -- a portion of a skull -- was positively ID'd as Laundrie's.

One thing that could be highly relevant in determining what happened to Gabby Petito -- the contents of Laundrie's backpack, which was found near the remains. The question ... did he leave a note detailing what happened to her.