Federal and local authorities are searching for a missing 15-year-old Louisiana girl who may be on the run with an older man, according to her family and police.
Domeanna Spell -- who is from Port Barre, about 50 miles west of Baton Rouge -- was last seen around 7 a.m. Thursday after she got off the school bus at Port Barre High School, said the Port Barre Police Department.
Authorities believe she may have run away with 47-year-old Cory Shane Disotel of Port Barre, a family friend.
Spell's sister said the teen had a relationship with Disotel.
(MORE: Tennessee teen taken by high school teacher says he threatened her to make her go on the run with him)"Domeanna started babysitting for his granddaughter, then come to find out there was no granddaughter there to really be babysitting," older sister Jerrie Cradeur, 29, told ABC affiliate KATC in Lafayette.
"I don't know when the relationship started," Cradeur told KATC. "When it was brought to my mom's and them attention, they said that he needed no contact with them... no contact with my sister," she added.
"Her family loves her and her friends are concerned," Port Barre Police Chief Deon Boudreaux told ABC News Tuesday. "They do miss her and they're worried about her. They just want her to come home."
(MORE: Timeline of teenager's relationship with 45-year-old man, journey to Mexico and back)"We want her to know that we're on her side," Cradeur said. "It's hurting us bad... I hardly eat. Me, my sister-in-law, my sister, we barely sleep."
But Cradeur vowed to "keep fighting. "
"I will keep looking, even if it's months from now," she said, "until we find her and she comes home."
Spell, who the FBI says may have changed her appearance to conceal her identity, has light brown hair and blue/hazel eyes. She stands 5-foot-2 and weighs about 105 pounds, according to authorities.
She may be in a silver 2003 Honda Civic, the FBI said.
Anyone with information can call 1-800-CALL FBI.