Gabby Petito's Mom Files Lawsuit Against Brian Laundrie's Estate

Gabby Petito's mother, Nichole Schmidt, has filed a wrongful death lawsuit against the estate of her daughter's deceased killer, Brian Laundrie ... seeking around $30k in damages.

Laundrie's family attorney, Steven Bertolino, tells TMZ … the filing of the wrongful death lawsuit by the Petito family was fully expected and most likely will not be defended.

He says, "The Petitos will have gained nothing more than a piece of paper that tells them what everyone already knows - which is that Brian was responsible for Gabby’s death as indicated by the FBI."

According to the lawsuit ... Laundrie killed Gabby and her parents had to cover funeral and burial expenses. They also claim they've suffered a loss of care and comfort from their daughter.

As for why only $30k, when they could have sued for 7-figures for the murder of their daughter, we're guessing it's because the funds just aren't there.

As we reported ... Gabby's parents sued Brian Laundrie's parents, claiming they were aware their son murdered their daughter before Brian's body was found in October.