Brian Laundrie Cause of Death Revealed as Suicide, Gunshot Wound to the Head

Brian Laundrie died as a result of a self-inflicted gunshot wound to the head -- this according to the family attorney.

TMZ spoke with Steve Bertolino, who says both of Laundrie's parents have been informed the cause of death was suicide. He tells us both parents are still mourning the loss of their son, and "hope these findings bring closure to both families."

Of course, this news comes after Laundrie's bones were examined by an anthropologist.

As we reported, Laundrie's body was found out at Myakkahatchee Creek Environmental Park by investigators, on the advice of his parents who suggested they search that same area again.

Remember, Brian's remains were in such a state that a medical examiner could not easily determine how exactly he'd died -- and this anthropology examination was commissioned to get to the bottom of it. One part of his remains that were intact enough were his teeth ... that's how they ultimately discovered this was, indeed, Brian -- with matching dental records.

This seems to finally close the book on this whole saga ... at least partially, anyway. We now know how exactly Brian and Gabby Petito died ... of course, we still don't know what happened in the middle -- namely, who killed Gabby ... and what Brian's role in that was.

As we reported ... Brian returned to Florida from a cross-country trip he'd gone on with his fiancee, but he came back by himself -- with no Gabby in sight. Shortly after touching down in North Port again and seeing his parents ... Brian himself disappeared without a trace.

There was a nationwide manhunt for him that carried on for weeks and weeks -- with different would-be sightings springing up all over the place.

In the end, the guy was literally in his own backyard (metaphorically) ... and the FBI said the reason they hadn't found him earlier is that the area he ended up being in was underwater for a majority of their initial search.