Florida police say the Gabby Petito case is officially a criminal investigation as her fiancé, Brian Laundrie, remains missing

• Florida police said Tuesday that the Gabby Petito case was now officially a criminal investigation.
• Police are continuing to search for Petito's missing fiancé, Brian Laundrie.
• A body believed to be Petito's was discovered at a campsite in Wyoming Sunday and the FBI later confirmed it was hers.

Florida police said for the first time on Tuesday that the Gabby Petito case was now officially a criminal investigation as authorities continue to search for her missing fiancé, Brian Laundrie.

"This is an FBI-led criminal investigation and North Port Police are assisting our federal partner in any way we can to bring this investigation to a close," Josh Taylor, a spokesperson for Florida's North Port Police Department, said in a statement.

Previously, the North Port Police Department was the lead investigating law-enforcement agency in the case, which has gripped the nation.

On Monday, the FBI raided the North Port home where Laundrie and Petito lived with Laundrie's parents after investigators announced on Sunday that a body believed to be Petito's was discovered at a campsite in Wyoming's Bridger-Teton National Forest.

An autopsy was performed on the body Tuesday and the FBI confirmed that it was Petito's.

Teton County Coroner Dr. Brent Blue's "initial determination for the manner of death is homicide," the FBI said.

"The cause of death remains pending final autopsy results," said the FBI.

Meanwhile, Taylor said on Tuesday that authorities would continue to search Sarasota County's Carlton Reserve for Laundrie. His parents told police that the 23-year-old North Port, Florida, man went for a hike in the nature preserve a week ago and never returned.

The 25,000-acre reserve, Taylor said, "is a vast and unforgiving location at times."

Petito, 22, was reported missing by her family in New York on September 11, 10 days after Laundrie returned home from a cross-country road trip out West in the van the couple had been driving in - but without Petito.

Laundrie, who was named a person of interest in Petito's disappearance, quickly retained a lawyer and refused to speak to authorities about the case.

He was reported missing by his family on Friday.