Brian Laundrie's Parents Silent on His Whereabouts as They Leave Home

Brian Laundrie's been missing for nearly 6 days now, and his parents are still not talking as the search for him continues as a person of interest in Gabby Petito's death.

Laundrie's mother and father were leaving their home in North Port, FL Thursday morning when they were asked if they have any info on his whereabouts ... and they had nothing useful to say.

This has been par for the course ever since their son showed up at their doorstep September 1 without Gabby, his fiancee, even though they were on a long trip across the country.

Brian's family has not been forthcoming with many details, other than letting authorities know he went missing last Friday after he was named a "person of interest" in Gabby's case. They said he took his backpack and went for a hike, but never came back.

As we reported ... Gabby's body was found 2 days later at a state park in Wyoming, a spot she and Brian are believed to have visited in the days after they had a domestic dispute in Utah.

The coroner ruled Gabby's manner of death homicide, and while the obvious suspect is Brian ... he's not officially been named one by police, at least not until they find out where he's at.