(NewsNation) — Six weeks after a man from Michigan walked away from a rehab center, his family fears someone may have taken advantage of his vulnerability.

Kelly Lee Gravit wrestled with alcohol dependency since he was a teen. His problem was exacerbated by a serious car accident when he went headfirst through a windshield at 130 miles per hour and sustained a closed head injury.

For years, Kelly tried to kick his alcohol habit, going in and out of rehab. Sometimes it would work for weeks, once as long as six months.

On Friday, Nov. 10, Kelly decided to try another attempt at sobriety. He checked himself into the Sacred Heart Rehab Center in Berrien County, Michigan, to detox from alcohol.

Tracy Carter, Kelly’s sister, told NewsNation he was excited to go to treatment.

“He was excited and saying he was going to do it this time,” Carter said.

Less than 30 hours later, Kelly walked out of the building, never to be seen again.

His family has been desperately searching for him.

“Everybody’s devastated,” Carter said. “Like, this doesn’t happen, this happens on TV, not at home in our family. It’s shocking. It still doesn’t even seem real.”

The rehab center reached out to Kelly’s mother the next day to let her know he was missing. Kelly’s niece, Brittany Backus, took her dog and walked around the wooded area surrounding the rehab center looking for Kelly. She ran into another patient at the facility who told her how Kelly was behaving just before he went missing.

“He was hallucinating a little bit before he went missing,” she said. “He told me Kelly took off walking toward the juvenile center and that somebody left in their car to go look for him right after and he was already gone.”

Gary Gravit, Kelly’s father, said Kelly’s head injury makes him vulnerable.

“Right now, it’s a 12-year-old in a 49-year-old’s body who’s missing,” he said.

Kelly’s family says the clues in the case are not adding up.

The family got help from an outside police force in Coldwater County, Michigan, who sent dogs to track Kelly’s scent. The rehab center said Kelly walked out the door and walked to the road in one direction, but the dogs picked up his scent going the opposite way.

Berrien County police also sent drones to search the area. They told NewsNation that Kelly’s case is an active investigation, but they also said because Kelly is a grown man, he may have wanted to leave and had someone he knew pick him up to avoid rehab.

But Kelly wasn’t allowed to use a phone at the center to call someone. Family members say the police’s theory is just not possible.

“He doesn’t have options for people to call. He doesn’t even have his teeth,” Carter said. “It just doesn’t make any sense why he would leave without his teeth and never call his mom, who he’s talked to every day for the last 30 years. Something’s not right.”

Kelly’s family says the rehab center has not been as helpful to them as it has been in the past.

“When we were out there looking for him, they told us to get off their property and that we couldn’t look for him out there,” Carter said.

Kelly’s family is hoping that he’s out there somewhere and someone will help him find his way home.

“I guess I’m praying for a miracle and preparing myself for the worst,” Gary said.