Investigators searching for Gabby Petito, the 22-year-old woman who went missing during a cross-country trip, are expressing frustration that Petito's boyfriend has not shed any light on her possible whereabouts.
In June, Petito and her live-in boyfriend, Brian Laundrie, left on a trip from the Florida home they shared with Laundrie's parents in Petito's 2012 white Ford Transit, North Port Police Chief Todd Garrison told reporters in a news conference Thursday afternoon. They intended to drive west, visiting state and national parks along the way, Garrison said.
"Two people went on a trip. One person returned," he said. "And that person that returned isn't providing us any information."
Petito's family said she maintained regular contact with them throughout the journey, and she and Laundrie documented their travels on Instagram and YouTube. Posts show them at the Mystic Hot Springs in Utah on July 26 and on a large rock structure at Arches National Park in Grand County, Utah, on Aug. 12, the same day police in Moab, Utah, responded to an incident involving an altercation by the couple that was called in by a witness. That interaction was captured on police body camera, Garrison said, not elaborating on what was seen in the footage.
Communication from Petito "abruptly stopped" toward the end of August, Garrison said, adding that investigators have not yet pieced together a complete timeline of Petito and Laundrie's travels.
Petito was last seen leaving a hotel in Utah with Laundrie on Aug. 24. The next day, she spoke to her mother, Nichole Schmidt, informing her that their next stops would be Grand Teton and Yellowstone, Schmidt told ABC News earlier this week.
"She sounded good and excited to continue her trip and excited to start her YouTube channel," Schmidt said in tears. "She seemed OK."
Schmidt received two text messages from Petito's phone since Aug. 25, but there were no photos or details from the trip, so it is unclear whether Petito actually sent those texts, Schmidt said.
Laundrie returned to Florida with Petito's van on Sept. 1, police said. Petito's family reported her missing on Saturday after they hadn't heard from her in more than two weeks.
Laundrie, named a person of interest in the case on Wednesday, has not made himself available to speak with investigators, despite numerous pleas from the police department and Petito's parents, authorities said.
The latest statement from the attorney representing the Laundrie family, Steven P. Bertolino, said he's advised Laundrie not to speak with authorities.
"Many people are wondering why Mr. Laundrie would not make a statement or speak with law enforcement in the face of Ms. Petito's absence," the statement read. "In my experience, intimate partners are often the first person law enforcement focuses their attention on in cases like this, and the warning that 'any statement will be used against you' is true, regardless of whether my client had anything to do with Ms. Petito's disappearance. As such, on the advice of counsel, Mr. Laundrie is not speaking on this matter."
The statement continued: "I have been informed that the North Port, Florida, police have named Brian Laundrie as a 'person of interest' in this matter. This formality has not really changed the circumstances of Mr. Laundrie being the focus and attention of law enforcement and Mr. Laundrie will continue to remain silent on the advice of counsel."
While police are still treating Petito's disappearance as a missing persons case, Garrison acknowledged that investigators have grown weary of Laundrie's refusal to speak to them, even if he is "exercising his constitutional rights" to remain silent.
"We share that frustration with the world," Garrison added.
During the press conference, Petito's father, Joseph Petito, made an emotional plea to Laundrie, his family and the public to help find his daughter.
"I'm asking for help from everyone here," he said. "I'm asking for help from everyone at home. I'm asking for help from the parents of Brian.
"There is nothing else that matters to me now. This girl right here. This is what matters."
ABC News' Will Gretsky contributed to this report.