Authorities search Grand Tetons for any sign of Gabby Petito

GRAND TETON NATIONAL PARK, Wyo. (CNN) – The family of a missing woman believes the family of her boyfriend is keeping information from the police.

Gabby Petito’s own family reported her missing on September 11th. The 22-year-old was traveling with her fiancé, Brian Laundrie.

Police believe at some point they were in the Grand Teton National Park in Wyoming. National park investigators, the FBI, and local police are searching the park for any sign of her. Laundrie came back from the trip without Petito.

Laundrie’s sister said she has not talked to her brother since that trip. But Petito’s dad, Joseph Petito, believes there is more to her story. He said, “Well, if you love Gabby as your sister and you knew your brother was home on the 10th, and, no Gabby to be found who lives in that house, and told no one… Okay. She is a mother and she’s got kids. So I’m hoping that the pleas and the begging and the community and the, you know, entire damn planet knock some sense into her, where she’s like, ‘I got to speak. I can’t live with this on my conscience.'”

Investigators also believe Laundrie and those around him are withholding critical information related to her disappearance.

Police say Laundrie has invoked his Fifth Amendment right to remain silent and he is refusing to come forward.