DURANGO, Colo. -- The father of a 13-year-old boy who went missing in 2012 and whose remains were found seven months later in southwestern Colorado was named Wednesday as a person of interest in the case.

The coroner's office had ruled the manner of death as undetermined, but on Wednesday, the sheriff's office said it was reclassified as a homicide.

Elaine and Mark Redwine CBS Denver

Mark Redwine's behavior and inconsistent statements throughout the investigation into Dylan Redwine's death led to the designation, according to officials with the La Plata County Sheriff's Office. They did not elaborate, and Mark Redwine could not be located for comment.

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Dylan lived north of Colorado Springs with his mother but went to his father's home near Vallecito Reservoir northeast of Durango for a court-ordered visit in November 2012. Mark Redwine has said he returned home from doing errands Nov. 19 to find his son gone. Mark Redwine says he last saw his son asleep that day, reports CBS Denver.

Investigators said last month they had developed a person of interest in the case, but didn't reveal who the person was. Mark Redwine told the Denver Post at the time that it may have been him.

Sheriff's office spokesman Dan Bender told The Denver Post in July that two searches in June near where the remains were found turned up items of interest. Another search of the area is planned in September.

Also on Wednesday, the sheriff's office said Dylan's mother, her other son and her husband were cleared of any involvement in the boy's disappearance and death.

"Today was a good day on our journey towards justice for Dylan," Elaine Redwine, the boy's mother, told KMGH-TV in Denver.

The case got national attention when Dylan Redwine's parents blamed each other for his disappearance publicly on the "Dr. Phil" show. Elaine Redwine still believes her ex-husband is responsible for their son's death, reports the station.

Mark Redwine reportedly denies involvement.