The body of a 7-year-old boy found in a Denver storage unit was encased in concrete, 9Wants to Know has learned. 

Caden McWilliams may have been dead since May. The Denver Office of the Medical Examiner had to use DNA analysis to ultimately positively identify him, according to a news release distributed on Friday. 

How he died has not yet been determined, the medical examiner said. 

The boy’s mother, Elisa Pankey, was formally accused of killing him Monday by Denver prosecutors. 

When his body was found Dec. 23 in a storage unit in the 5000 block of East Evans Avenue, it was encased in concrete, according to sources familiar with the investigation. The development was first reported by The Denver Post.

Pankey, 43, is charged with one count of child abuse resulting in death and one count of abuse of a corpse, the Denver District Attorney’s Office announced Monday morning.  She turned herself into Denver police last week.

RELATED | 7-year-old boy found in Denver storage unit may have been dead since May, records say

This comes after the Aurora Police Department contacted their counterparts in Denver on Dec. 23 regarding a missing 7-year-old boy. That child, since identified as Caden McWilliams, was found that same day in a storage unit at 5005 E. Evans Ave.

Denver homicide records indicate that police believe McWilliams could have been in the storage unit as early as May. 

Denver police spokesperson John White said the boy was last seen in school on May 24. The last day for Denver Public Schools students was on May 31, according to district spokesperson Will Jones.

Citing the ongoing nature of the investigation, a judge has sealed all of the records related to Pankey’s arrest.

RELATED | Husband of mom, who turned herself in after 7-year-old found dead, in court for assault charges

According to Colorado Bureau of Investigation records, Pankey has a criminal history in Colorado dating back to 2000, when she was arrested for driving under the influence.

The day before her son was found dead, the records say she was arrested in Aurora for heroin possession.

Pankey is being held in the Downtown Detention Center on a $250,000 bond. Her next court date has not yet been set.

Police ask anyone with information about the case call Crime Stoppers at 720-913-STOP.

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