(CNN)The search for the now-missing fiancé of 22-year-old Gabby Petito is focused on a Florida nature reserve, where 50 officers from five local agencies and FBI agents scoured the area Saturday, according to North Port Police spokesperson Josh Taylor.
During a Saturday news conference, Taylor said Laundrie has an "enormous amount of pressure" on him to provide answers following Petito's own disappearance.
Brian Laundrie's family told police Friday night they have not seen the 23-year-old since Tuesday. Police said at that time Laundrie is not wanted for a crime, and that authorities are working "multiple missing person investigations."
Investigators were searching for Laundrie at the "vast Carlton Reserve" near Venice, Florida, North Port Police said on Twitter Saturday. The search effort included the use of drones and bloodhounds who had used articles of Laundrie's clothing taken from his home to get his scent, Taylor said.
The search ended Saturday evening due to darkness and will resume Sunday morning, North Port Police said in a tweet.
Laundrie's family told police he left home with his backpack Tuesday and told them he was going to the reserve, Taylor said Saturday. Police believe the vehicle he was driving may have been at the reserve too, but has since been returned to the Laundrie's home.
Police initially focused their search on a nearby park about 200 acres large, but throughout the day it had spread into the reserve, which is about 25,000 acres, he said.
When asked why Laundrie's family didn't tell police of his whereabouts until Friday, Taylor said, "that's a great question."
"You know we've obviously been trying to reach the family to get answers in this case since (last) Saturday," Taylor said. "The first time that we've had any in-depth conversation with them was yesterday when their attorney called and said the family was concerned about Brian's whereabouts."
Laundrie family attorney Steven Bertolino said Friday that Laundrie's whereabouts "are currently unknown."
Richard Stafford, the attorney for the Petito family, said in a brief statement sent to CNN, "All of Gabby's family want the world to know that Brian is not missing, he is hiding. Gabby is missing."
Search for Petito is now a week old
Law enforcement began investigating Petito's disappearance on September 11, when Petito's family reported her missing after they were unable to contact her for several days. Prior to her disappearance, Petito had been traveling with Laundrie on a road trip through several western states.
Laundrie returned to North Port without Petito September 1, according to police. Officials later found the van the couple had been traveling in at the home Petito shared with Laundrie and his parents in North Port.
On Saturday, the FBI said the search for Petito included ground surveys being conducted in Grand Teton National Park with the National Park Service, the Teton County Sheriff's Office and the Jackson, Wyoming, police.
"This is an active and ongoing investigation, so we ask the public to maintain distance from any law enforcement personnel, equipment, vehicles, and their related activity for the safety of the public in these remote areas and to protect the integrity of our work," the FBI's Denver field office said in a tweet Saturday afternoon.
In a statement issued to NBC before it was reported Laundrie's whereabouts were unknown, family attorney Bertolino said Laundrie would not speak about the matter because "intimate partners are often the first person law enforcement focuses their attention on in cases like this and the warning that 'any statement made will be used against you' is true, regardless of whether my client had anything to do with Ms. Petito's disappearance."
North Port Police Chief Todd Garrison told CNN's Don Lemon earlier in the week that Laundrie had invoked his Fifth Amendment right, which generally means a person cannot be forced to make statements they feel might be negative or used against them.
Police previously visited the home but the family refused to talk and instead gave authorities the information for their attorney, Taylor said this week.
On Saturday, he reiterated police were limited in what they could do because "we don't have a crime."
"We can't go just pulling people in, he certainly has the Fifth Amendment not to speak, and we're respectful of that," he said. "We get it. We're frustrated."
Petito stepfather: 'I don't know what to believe'
Petito's stepfather said Friday he is happy Laundrie's parents called police, but said, "I don't know what to believe."
Jim Schmidt told CNN's Chris Cuomo he was "caught off guard" by the news shared moments earlier that Laundrie's family spoke with authorities, saying he hadn't even had a moment to digest it.
"All that matters is finding her and bringing her home," Schmidt said.
"We're still trying to get the word out there and try to find that one person that might have some details that we need," Schmidt said. "Just trying to get out there and find that person and hopefully they can help us with anything that will bring her home."
When asked if there was anything from the last few times he contacted Gabby that would be helpful now, Schmidt said, "I'm not sure. We've been analyzing everything as much as we can, and your mind races in a million different directions when you're trying to put something like this together and it's -- we're still trying to get a full grasp on the entire situation."
Schmidt asked for the media to "just keep getting the word out," adding, "Some different photos, not just the ones that have been out there, maybe that sparks something in the public that somebody didn't recognize before and just keep getting that word out there and keep this fresh in the media so it keeps going until we find her."
The FBI has released a new Missing Person poster, asking for help in the search for Petito.
Campsite reviews appear to show the couple this summer
Before they vanished, Petito and Laundrie appeared to have left reviews on an online camp community app called The Dyrt. A photo of the couple was posted on The Dyrt two months ago and tags their social media accounts.
An account linked to the couple lists campgrounds in Colorado, Idaho, Montana, Washington, Wyoming, and Utah, as well as left reviews of campsites where Petito was last seen. Camping spots to the Grand Teton National Park were saved on the profile.
According to a timeline of events provided Friday by Petito family attorney Stafford, Gabby FaceTimed with her mother on August 24, saying she was leaving Utah and headed to the Tetons.
This photo of Petito and Laundrie was posted on the online camp community app.
Their most recent review is about Arches National Park in Utah in July, in the same county where Moab police had an interaction with Petito and Laundrie two weeks later.
At the time, officers with the Moab City Police Department responded to reports of disorderly conduct involving Petito and Laundrie, which ended with a report describing them as having "engaged in some sort of altercation."
The officers who responded to the incident suggested Laundrie and Petito should separate for the night, according to the report, and no charges were filed.
One of the officers who responded to the scene wrote in the police report Laundrie said the pair had been traveling together for "the last four or five months."
