Who is Brian Laundrie's older sister, Cassie Luycx?

Cassie Luycx, 31, has laid low following the disappearance and death of Gabby Petito, who would have been her future sister-in-law, and during the manhunt for her younger brother, 23-year-old Brian Laundrie, who is now a fugitive wanted for alleged debit card fraud and a person of interest in Petito's death.