Letecia Stauch asked her teen daughter to buy trash bags, carpet cleaner and baking soda hours after killing her stepson Gannon Stauch in his bedroom, according to an arrest affidavit obtained by InsideEdition.com.
Investigators believe Letecia used the items to clean up the murder scene before reporting the boy as missing to police, the affidavit said. The request for the items was sent via text message, and investigators found a receipt documenting the purchase.
Letecia was arrested and charged with Gannon's murder on March 2.
On March 23, Gannon's remains were found in Florida, more than 1,000 miles from his suburban Colorado home, according to authorities.
The affidavit of probably cause to arrest Letecia was filed Feb. 28 and surfaced on social media Thursday. It gives new details of what investigators say happened the day Gannon was killed and the timeline of events in the days after.
The affidavit alleges Letecia killed Gannon on the afternoon of Jan. 27. Investigators said they found evidence of blood on a mattress in the boy's bedroom, as well as on the walls and floors of the room and inside Letecia's SUV.
After allegedly cleaning the crime scene, Letecia then reported Gannon missing. She said he had stayed home from school that day, and she last saw him in the afternoon when he left for a friend's house, authorities said.
The next evening, Letecia allegedly dumped Gannon's body off a highway in Douglas County, Colorado.
In a Jan. 29 interview with investigators, Letecia changed her story and said she had been held at gunpoint inside the home and raped by a Hispanic man named "Eguardo" who then abducted Gannon.
Investigators were critical of the rape story because it would have meant she waited two days before reporting it to police. She also "refused to cooperate" with investigators by providing more evidence about the alleged incident, the affidavit said.
Letecia faces 13 charges, including first-degree murder, child abuse resulting in death and tampering with evidence.