According to an affidavit, her 13-month-old son, Joseph, drowned Sept. 20 after Johnson left him alone in the bathtub.
Johnson said she was giving the child a bath in the morning after breakfast, according to the affidavit, and that the water level was a little higher than usual, but she apparently figured it was safe.
She then went into the next room logged onto Facebook, according to police.
Johnson told police that she heard the boy splashing around in the tub as she checked in on her friends, shared videos and played a game called Café World, in which the user runs a digital restaurant.
The woman checked on the infant once before returning to her game.
After several more minutes, when she didn’t hear anymore playing sounds, she went into the bathroom and found the child slumped over in the tub, the affidavit states, according to CNN.
Johnson called 911, and the boy was airlifted to a Denver-area hospital, where he later died.
The autopsy listed anoxic brain injury, cardiac arrest and drowning as the cause of death.
This wasn’t the first time the baby had been left alone.
Johnson told police that she had left the boy in the tub before, saying that he was an independent baby and that he wanted to be left alone, according to CNN, and Johnson’s mother told cops that she had warned her daughter about leaving the boy in the tub.
Johnson was being held Tuesday on $100,000 bond. A bond hearing is scheduled for Jan. 31.
If convicted, the Johnson could face as many as 48 years in prison.