A lawyer for Mr Laundrie's parents confirmed they were in the area where the items were discovered on Wednesday.
"Chris and Roberta Laundrie were at the reserve earlier today when human remains and some of Brian's possessions were located in an area where they had initially advised law enforcement that Brian may be," Steve Bertolino said.
He added the couple would "wait for forensic identification of the remains" before commenting further.
Mr Bertolino earlier told reporters that "some articles" had been discovered on a trail frequented by Mr Laundrie within a park where a car driven by him was earlier discovered.
The FBI's Tampa field office tweeted after the discovery that the nature reserve was closed to the public.
FBI special agent Michael McPherson said that officers would likely be processing the scene for several days.
"I know you have a lot of questions, but we don't have all the answers yet," he told the media.