(CNN) -- On a cold, rainy night in late November, Douglas Wright sat amid brambles and thick East Texas underbrush, watching over the body of his 28-year-old son, Alfred, who had disappeared almost three weeks earlier.
"His spirits got to me: 'Daddy, I knew you would find me,'" Wright says, recalling the relief that had washed over him.
Sabine County sheriff's deputies had searched for Alfred Wright but didn't find him, and volunteer searchers later found his body, his family says.
A medical examiner says the death was accidental, but the family rejects that notion, citing what a different pathologist says appears to be "severe trauma" to his body. The Texas Rangers and FBI are investigating.
Alfred Wright was last seen around dusk on November 7. The physical therapist was on his way to treat a patient. He had been having trouble with his pickup and pulled into CL&M Grocer, one of the few stores along an isolated stretch of Route 87.
He called his wife, Lauren, and gave her directions to the store. Because their two young sons were home sick, she called his parents, who immediately left on the hourlong drive. What happened next changed everything.
"The last time I called him, I just heard heavy breathing. He was in distress of some sort. He was not responding to anything I was saying," Lauren Wright says.
Around 6 p.m., Alfred Wright disappeared from where he was last seen alive. When his parents arrived about 20 minutes later, his truck was in the parking lot, but he was nowhere to be seen. His father asked the store clerk what happened. He says she told him that she was out having a smoke when Wright "all of a sudden put his cell phone in his sock and took off like the truck was going to blow up."
The clerk did not want to be interviewed on camera but did tell CNN that Wright "left on his own free will," a phrase she repeated several times.
The next day, his personal effects, including his watch and ID, turned up on a nearby ranch. Deputies searched the property with cadaver dogs. His family says it was told by the deputies that Wright's scent had "disappeared" at a nearby creek.
Four days after Wright vanished, Sabine County Sheriff Thomas Maddox called off the search, telling the family, "Your son's just a missing person. My guys are tired. We've exhausted our resources and funds. We're done," family lawyer Ryan MacLeod says.
Family members say the sheriff told them that "there was no foul play" and that Wright's disappearance was probably "drug-related," most likely related to methamphetamine.
The sheriff's daughter and Wright apparently knew each other through their health care jobs, which made the sheriff's actions even more surprising to the Wrights, who were left to search for their son on their own.
He had been missing for 19 days when, during Thanksgiving week, dozens of volunteers did their own search in the cold and rain. Wright's body was found nearly three weeks after his truck broke down, in an area of the ranch supposedly already searched by deputies.
'He was neatly laid'
Walking to the spot, Douglas Wright describes the position in which his son lay: "His head was in this area, and his feet was back here. He was just, if I might say, he was neatly laid. He was neatly laid."
Alfred Wright was wearing only boxer shorts, tennis shoes and a single sock, inside of which was his cell phone, just as the clerk had described. The second sock was under the body. "I was told by the mortician at the autopsy that when they pulled off his left sock, his keys was under his left foot in his shoe," his father says.
"What was weird about his sock," says his father, is that it "was clean, and his sock was pulled up with his phone stuck in it as if he was in a Sunday school class. Neat. His tennis shoes was very clean."
And not just the position of the body seemed strange. "This is the first thing I noticed -- how smooth his forearms and his back was. No scratches at all," his father says. After just one day, he and the other volunteers were caked in mud and their clothing torn from brambles, he says.
Alfred Wright was missing an ear, two front teeth, and his throat appeared to be cut. The medical examiner attributed the trauma to "animal and insect activity." What's more, in an echo of the sheriff's prediction, the coroner's toxicology report described Wright's body as filled with drugs -- cocaine, meth and amphetamines. His death was ruled "accidental" due to a "combined drug intoxication."
His family doesn't believe it. Family members say they never saw him do drugs, nor had his personality changed to suggest he was using drugs. They say he was the fun-loving, hardworking father he had always been. They want to know if the drugs entered his body while he was missing.
Suspicious of the investigation, the family hired their own pathologist, who ultimately did a separate autopsy and, contrary to the medical examiner, found what appears to be "severe trauma to the neck and head."
A month after Wright's body was found, Maddox handed the investigation over to the Texas Rangers. They have called the death "questionable" and say the autopsy is just one part of an active investigation. The week CNN was in Sabine County, the Texas Rangers announced they had called in the FBI to assist.
After Alfred Wright's death, wife Lauren went through bank records. She found three charges her husband made at local hotels when she and the children were away the month before he died. Texas Rangers are pulling video from one of the hotels to review it for possible evidence.
CNN's Ross Levitt contributed to this report