By Dan Whitcomb

(Reuters) – The exhaustive search for slain travel blogger Gabby Petito’s fiance in a vast Florida wilderness entered a sixth day on Thursday as the mystery deepened around a case that has engrossed Americans.

The divers joined FBI and police agents in searching for Brian Laundrie (23) in the alligator-infested Carlton Reserve. But a spokesman at nightfall said that they found nothing.

The reason authorities believe Laundrie (whom police refer to as a “person-of interest”) in the case is not known. This comes more than one week after Laundrie told his family that he was going there alone for hiking.

North Port police state that Laundrie’s family did not notify them of his disappearance until September 14, just three days after they last saw him. There are more than 80 miles (128km) worth of hiking trails in the Carlton Reserve, but it is dominated with swampy water.

Since Petito (22 years old) was reported missing in September 11, many Americans have been closely following the case. Laundrie, who had just returned from their cross-country road trip that Laundrie documented in social media posts, was found dead at North Port ten days prior.

Petito’s remains were found in Wyoming’s Bridger-Teton National Forest on Sunday. It was less than 1,000 feet from the spot where another couple of bloggers captured video of Petito and her white Ford Transit, parked on a dirt road.

After identifying Petito’s body, Teton County Medical Examiners declared the death of Petito a homicide but didn’t make her cause of death public.

‘NO SERVICE IN YOSEMITE’

Petito and Laundrie left her home state of New York in July, heading west on what they called a “van life” trip. As they traveled across Kansas, Colorado, and Utah, the couple posted pictures to social media.

Petito last appeared in public on Aug. 24, when she was departing from a Salt Lake City Hotel. Her final picture was posted the following day.

Petito’s family thinks she was on her way to Grand Teton National Park. She was found dead at the park’s edge, near the Spread River.

The Laundrie family’s North Port residence was searched by investigators last week. There were boxes of cardboard packed in a van, and a Ford Mustang silver sedan towable.

Schmidt became suspicious after investigators requested search warrants. They cited texts Petito had sent her mother Nicole Schmidt from her cell phone.

Petito received the final text message on Aug. 30, which read: “No Service in Yosemite.” Laundrie and Petito are not known to have visited this national park while they were away.

An emergency caller reporting that Laundrie was hitting Petito at the Moonflower Community Cooperative of Moab (Utah) on August 12 reported this to 911.

Moab police pulled over the couple with their van near Arches National Park. The encounter was captured on body camera. Petito is seen sobbing and describing a fight that escalated to her hitting Laundrie while he drove his van.

Petito and Laundrie were not taken into custody by the officers, but they told them that they should spend the night together.