A Fort Lupton mother is scheduled to be arraigned Friday in the drowning of her 1-year-old son last September.Shannon Johnson, 34, admitted to police that she was on Facebook playing Cafe World, checking on a friend's status and sharing videos in the living room, while her son was in the bathtub, according to an arrest affidavit obtained by 7NEWS.Johnson told police her son was playing in the bathtub for about 10 minutes and she checked on him once. Johnson said that about three more minutes went by and she didn't hear her son playing, so she went to check on the baby and saw him sideways with his face in the water, according to the arrest affidavit.Johnson told police she grabbed the boy out of the water and she heard some gurgling.An ambulance took the boy to a nearby fire station where he was airlifted to Children's Hospital. He was pronounced dead at 4:30 p.m.When the detective asked Johnson why she would leave a 13-month-old in the bathtub alone, Johnson said he really wanted to be left alone and he was a very independent baby. In the affidavit, Johnson also said she didn't want her son to be known as a "mamma's boy."She told detectives that she knew what it was like to be told no and she didn't want her baby to be told no.Johnson told police she gave the baby a bath everyday, sometimes twice a day. She said on the day the baby died, the water level may have been a little higher than usual.Johnson told police her son had a seizure at his grandmother's house a month earlier. She was given anti-seizure medicine to give the boy if he was having a seizure. Johnson said doctors did not diagnose what caused the seizure and there were no other seizures.The investigation into the boy's death was delayed while investigators waited for the final autopsy report. That report came back Jan. 3. It said the baby died of anoxic brain injury, cardiac arrest and drowning, according to the arrest affidavit.Johnson was arrested Tuesday.Weld County Undersheriff Margie Martinez told 7NEWS that Johnson could face a charge of child abuse resulting in death.Martinez said Johnsons mother told investigators that shed warned her daughter of the danger of leaving the toddler unattended in water just days before he drowned.She told her she wouldnt do it anymore, Martinez said.The suspect is due in court Friday morning.Read the arrest affidavit.