An Idaho grandmother has been arrested after investigators discovered a body believed to be her 8-year-old granddaughter, whom she reported missing last week, inside a trash bag, according to reports.

Connie Ann Smith, 54, first reported Taryn Summers missing on April 12, telling deputies she had run away, according to court documents obtained by KTVB-TV.

THREE IDAHO CHILDREN  REPORTED MISSING, MAY BE TOGETHER, SHERIFF'S OFFICE SAYS

On April 13, investigators carried out foot and drone searches of the area but found no sign of Taryn, the documents said. Idaho state forensic teams returned the next day and found a spot of blood on Taryn’s bedroom wall.

Smith, who was initially charged with first-degree murder, is now facing felony charges of failure to notify of a death and destruction of evidence, local news outlets reported. (Ada County Sheriff's Office)

A subsequent search of the area led to the discovery of a girl’s body inside a black plastic trash bag in the backseat of a black Lexus parked in front of Smith’s home, Idaho News 6 reported. The Lexus was reportedly registered to a family member and Smith was seen driving it the day Taryn went missing.

The Gem County Sheriff’s Office on Friday announced the discovery of a body and an arrest in Ada County. The statement said the body discovered was believed to be Taryn. It did not identify the subject who was arrested.

Taryn, center, was initially believed to have gone missing along with two older children, 17-year old Tristan Conner Sexton and 14-year-old Taylor Summers. The two older children were not found with Taryn and are believed to be safe, authorities said. (Gem County Sheriff's Office)

Smith was initially arrested in Ada County on Thursday and booked on a charge of first-degree murder, according to online jail records. She is no longer facing murder charges, and is instead facing felony charges of failure to notify of a death and destruction of evidence, local news outlets reported.

Prosecutors said additional charges are expected. A preliminary hearing for Smith was scheduled for May 3.

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Taryn was initially believed to have gone missing along with two older children, 17-year old Tristan Conner Sexton and 14-year-old Taylor Summers. Local news outlets described the three children as siblings.

The Gem County Sheriff’s Office said the two older children were not found with Taryn but are believed to be safe.

"Law enforcement has been in contact with Taylor and does not believe her to be in danger at this time," police said. "Family has been in contact with Tristan Sexton and law enforcement does not believe him to be in danger at this time."