The FBI has released a final investigative update on the Gabby Petito case, saying that Brian Laundrie left behind a written confession.

They say the investigation "did not identify any other individuals other than Brian Laundrie directly involved in the tragic death of Gabby Petito."

The updates come four months after Petito first disappeared in mid-September while on a cross-country road trip with her fiancé, Laundrie.

The Blue Point native's remains were found on Sept. 19 in Wyoming. The FBI says she was strangled and suffered blunt force trauma to the head and neck.

The FBI also announced Friday that text messages were sent between Laundrie and Petito's phones after Petito was already dead. According to the FBI, the messages were sent by Laundrie as a way to deceive law enforcement into believing that Petito was still alive.

Laundrie's remains were found in October in Florida near his family's home. He had died of a self-inflicted gunshot wound.

The FBI found a backpack and a notebook belonging to Laundrie near his skeletal remains.

They say the notebook contained written statements by Laundrie claiming responsibility for Petito's death.

Ralph Cilento who works with John Jay College of Criminal Justice says the notebook confession brings the investigation to a conclusion that makes sense.

"What the notebook does is, No. 1 it rules out any other suspects as far as the FBI is concerned," Cilento says. "And it affirms to them what they had suspected all the time based on the evidence that they had."

Petito's family attorney Richard B. Stafford released a statement Friday, saying "The quality and quantity of the facts and information collected by the FBI leave no doubt that Brian Laundrie murdered Gabby."

News 12 reached out to Laundrie's family attorney, but he refused to comment.

Both the Laundrie and Petito families are working to retrieve items that belonged to their children and are currently in the FBI's possession.