Brian Laundrie, only person of interest in Gabby Petito case, allegedly last seen one month ago

Question looms - Who strangled Gabby Petito?

Now that the Teton County, Wyoming coroner, Dr. Brent Blue has determined through autopsy that Gabby Petito was killed by strangulation and that her death was a homicide, the question of who killed her remains.

NORTH PORT, Fla. - The last time Brian Laundrie was seen was back on Sept. 13, according to his parents, authorities say. One month later, his whereabouts remain unknown.

Brian returned to his parents home in North Port on Sept. 1 in Gabby Petito's van – that they used in their cross-country trip – but without her. His family reported him missing on Friday, Sept. 17, saying they believed he left home on Tuesday, Sept. 14 in his silver Ford Mustang. However, last week, his parents backtracked, saying they now believe the day Brian left for his hike in the Carlton Reserve was Monday, Sept. 13.

Attorney Steven Bertolino, the Laundrie family attorney, said the Mustang was back at the Laundrie home Wednesday, Sept. 15.

Brian was Gabby's fiancé and is the only person of interest in her case. He remains missing, despite several weeks of searching in Sarasota County.

PREVIOUS: Gabby Petito's cause of death ruled strangulation; body was outside up to 4 weeks, Wyoming coroner says

Last Thursday, Brian's dad, Chris, spent three hours with investigators at the Myakkahatchee Creek Environmental Park, where the family thinks Brian was heading before he disappeared.

Gabby Petito autopsy

On Tuesday, the coroner in Teton, Wyoming revealed Gabby died by strangulation. The report was brief, but it answered several questions about her death.

During a virtual press conference, Dr. Brent Blue revealed that it was estimated Gabby had been killed 3-4 weeks before her body was discovered, meaning she was likely killed shortly after August 25 when she made her last FaceTime call to her mom and her final social media post.

Teton County coroner releases final autopsy results in Gabby Petito's death

Teton County, Wyoming Coroner Dr. Brent Blue says Gabby Petito died by strangulation and confirmed her death has been ruled a homicide.

He said DNA samples were taken by law enforcement, which could help them zero in on a suspect. The FBI has also collected samples from the Laundrie home in North Port.

Brian has not been named a suspect, but he is wanted on a federal warrant for unauthorized use of her card. When the FBI announced the charges last month, they said a Capital One Bank card was used between Aug. 30 and Sept. 1, taking more than $1,000.

The attorney for Brian Laundrie and his family released a statement after Tuesday's press conference with the Teton County Coroner, saying:

"Gabby Petito’s death at such a young age is a tragedy. While Brian Laundrie is currently charged with the unauthorized use of a debit card belonging to Gabby, Brian is only considered a person of interest in relation to Gabby Petito’s demise. At this time Brian is still missing and when he is located we will address the pending fraud charge against him."

Gabby Petito’s family tells Laundries: Do the right thing

As the search for Brian Laundrie returned to the swampy Florida park, Gabby's family spoke to FOX News with a message for the Laundries.

MORE: Gabby Petito's parents say Brian Laundrie still alive, recall learning tragic news of daughter's death

Investigators are still asking the public for help in locating Brian. They say he is a white male, 5-foot-8 and weighing 160 pounds. He has brown eyes, very short brown hair, trimmed facial hair, and was last seen wearing a hiking bag with a waist strap.

Anyone with information is asked to call 1-800-CALL-FBI.

Cassie Laundrie speaks out with brother on the run after Gabby Petito's homicide

Brian Laundrie's sister, Cassie, told protesters outside her home that her family has been ignoring her following the disappearance of her brother and the death of Gabby Petito.

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Gabby Petito