Story highlights Alfred Wright was missing three weeks before his body was found

A coroner's report says his body was filled with drugs, and his death was ruled accidental

Family members say they never saw him do drugs

Texas Rangers say the death is questionable and called in the FBI to help investigate

The Department of Justice is investigating the death of Alfred Wright, a physical therapist who disappeared and died under mysterious circumstances in an isolated section of Texas, U.S. Rep. Sheila Jackson Lee said Monday.

Wright, 28, a resident of Jasper, Texas, was last seen alive November 7 when he stopped at a liquor store because he was having trouble with his pickup truck. He was on his way to treat a patient.

Local law enforcement authorities searched but gave up. His family found his partially clothed body 19 days later in an area that officers had supposedly searched.

Adding more confusion, a medical examiner said the death was accidental, but a different pathologist hired by the family said there appeared to be "severe trauma" to the body.

The federal investigation comes after reporting by CNN into the case . Lee, a Democrat who represents the 18th District of Texas, announced the investigation in a Monday press release. It wasn't immediately clear from the Justice Department when or how it will proceed with the investigation.

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Family members said Wright, married and the father of two young sons, called from the CL&M Grocery on Route 87, asking someone to pick him up because of problems with his truck. When they arrived, he was gone.

The next day, Wright's personal effects, including his watch and ID, turned up on a nearby ranch but the search for him turned up nothing. Family members say the sheriff told them "there was no foul play" and that Wright's disappearance was probably drug-related.

Family and friends kept searching. When found, Wright was wearing only boxer shorts, tennis shoes and a single sock, inside of which was his cell phone.

Wright was missing an ear, two front teeth, and his tongue. His throat appeared to be cut. The medical examiner attributed the trauma to "animal and insect activity." The coroner's toxicology report described Wright's body as filled with drugs -- cocaine, methamphetamine -- and his death was ruled accidental due to a "combined drug intoxication."

Family members said they never saw Wright do drugs. The family hired their own pathologist, who did a separate autopsy that found what appeared to be "severe trauma to the neck and head."

The Sabine County Sheriff's Department handed the investigation over to the Texas Rangers, who announced they had called in the FBI to assist.