June 30 (UPI) -- Lori Vallow faces additional charges in connection to the disappearance and deaths of her children in Idaho.
Vallow was charged with two counts of conspiracy to commit destruction, alteration or concealment of evidence late Monday night.
In a 16-page affidavit explaining the charges, police said she conspired with her husband, Chad Daybell, who is facing two felony counts of concealment or destruction of evidence, to cover up the deaths of her children Joshua "JJ" Vallow and Tylee Ryan. The children were found buried on Daybell's property.
The documents stated that Vallow provided false or misleading information to law enforcement regarding her son's whereabouts and encouraged her friend Melanie Gibb to not cooperate with law enforcement's investigation.
The charges came after Rexburg, Idaho, police served a search warrant at Daybell's home in Salem, but it wasn't immediately clear if they were related to the development in Vallow's case.
Police are now also saying they believe Tylee was 16 when she was killed, not 17 as previously stated.
Rexburg police detective Lt. Ron Ball said Tyle was originally reported missing in September, but later discovered she was last seen two weeks before her 17th birthday.
"Law enforcement has stated that Tylee was 17 at the time she went missing because we were not aware she was missing until several months after her 17th birthday," Ball wrote in the documents. "We now have reason to believe she was killed before her 17th birthday."
Vallow has been held on $1 million bail since her arrest in March, when she was arrested in Hawaii and charged with child abandonment and obstruction of justice.
She was set to make an initial appearance in court on Tuesday evening.