FBI agents search Brian Laundrie's North Port home

As police searched the North Port family home of Brian Laundrie for clues to the disappearance — and likely death — of his fiancée, new details emerged that suggest Gabby Petito may have disappeared weeks before her parents reported her missing.

• Police laid out a timeline in a search warrant last week for an external hard drive they found in the white Ford Transit van the couple drove on their road trip west.

Why it matters: The timeline details that Petito's mother received a text from Petito's phone on Aug. 27 that concerned her because it referred to Petito’s grandfather as "Stan." That seemed out of character.

• That was the last text she received from Petito's phone, but she didn't report her daughter missing until Sept. 11.
• The timeline then shows the white Ford Transit van owned by Petito was detected exiting I-75 at North Port at 10:26am on Sept. 1.
• If Laundrie was driving, it means he returned to North Port 10 days before Petito's parents reported her missing.

The latest: NBC News reports that a witness to the couple's dispute on Aug. 12 called 911 and said he saw "the gentleman slapping the girl."

Go deeper: Social media sleuths are rushing to help investigators crack Petito's disappearance, Mike Allen writes in Axios PM.