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NORTH PORT, Fla. (WFLA) — Brian Laundrie was the only person involved in the death of Gabby Petito and claimed responsibility for her death in his notebook, the FBI said Friday as the agency gets ready to close the investigation into the disappearance and death of the 22-year-old North Port woman.

The FBI has been the lead agency investigating the Petito case for several months now. Petito was found dead in Wyoming about a week after she was reported missing by concerned family members who had not heard from her since the end of August. Petito and Laundrie were on a road trip out west at the time.

“All logical investigative steps have been concluded in this case,” Special Agent in Charge Michael Schneider with the FBI in Denver said in a statement. “The investigation did not identify any other individuals other than Brian Laundrie directly involved in the tragic death of Gabby Petito. The FBI’s primary focus throughout the investigation was to bring justice to Gabby and her family.”

Petito was reported missing on Sept. 11 by family members who said they lost communication with her and were not getting answers from Laundrie’s family. The FBI said it started investigating on Sept. 12 and launched a search for Petito. One week later, they said a search team found her remains at the Spread Creek Dispersed Camping Area.

A coroner later said Petito died of “blunt-force injuries to the head and neck with manual strangulation.”

“While law enforcement investigated all logical leads, the investigation quickly focused on the last person believed to see her alive — Mr. Laundrie,” the FBI said Friday.

Laundrie returned home to North Port without Petito on Sept. 1, according to police. According to the FBI, he used Petito’s debit card while he was driving back to Florida from Wyoming. A federal arrest warrant was later issued for Laundrie in connection with the use of her card.

The FBI also revealed Friday that they found several texts sent between Laundrie and Petito’s phones after Petito’s death. The agency said Laundrie was trying to “deceive law enforcement by giving the impression that Ms. Petito was still alive.”

Laundrie was named a person of interest in Petito’s disappearance before her body was found, but was reported missing himself several days later.

After more than a month of searching, the FBI said Laundrie’s remains were found in a Sarasota County nature reserve in October along with a backpack, revolver and notebook. The FBI revealed Friday that Laundrie had written statements in the notebook claiming responsibility for Petito’s death.

A medical examiner later determined Laundrie died of a self-inflicted gunshot wound.

Family members of Petito, who met with the FBI in Tampa on Thursday, released a statement through their attorney shortly before the FBI announced its findings. The family said they had “no doubt” that Laundrie murdered her.

“We truly appreciate the FBI’s diligent and painstaking efforts in this extremely complicated case. The quality and quantity of the facts and information collected by the FBI leave no doubt [that] Brian Laundrie murdered Gabby,” the statement released by Rick Stafford said.

The Laundrie family’s attorney also released a statement Friday after the FBI findings came out.

“Gabby and Brian are no longer with their families and this tragedy has caused enormous emotional pain and suffering to all who loved either or both of them,” Steve Bertolino said. “We can only hope that with today’s closure of the case each family can begin to heal and move forward and find peace in and with the memories of their children. May Gabby and Brian both rest in peace.”

The families of Petito and Laundrie reached an agreement earlier this week to split the couple’s belongings once they’re released by the FBI.