To this day, no one knows where the baby is or if he's even alive.
Prosecutors said the baby was used to get back at the father after he broke up with her.
The baby's father is expected to take the stand Monday.
Thursday, on the first day of her trial, Elizabeth Johnson was in tears as prosecutors said she used her 8-month old baby, Gabriel, as a pawn.
"Gabriel Johnson was a pawn. He was a tool, he was a piece in a game, and the object of that game to her was to keep Gabriel Johnson from Logan McQueary--was to retaliate against Logan McQueary for breaking up with her," said prosecutor Elisa Ramunno.
Johnson is charged with kidnapping, custodial interference and conspiracy to commit custodial interference.
She originally told the baby's father she killed the 8-month-old, but recanted, telling police she gave the baby to a San Antonio couple.
The baby's father, Logan McQueary, is expected to take the stand Monday.
"You'll see Logan McQueary, I'm sure he will be quite effective as he was in the Tammy Smith case," said Marc Victor, Johnson's attorney.
McQueary's testimony helped convict Tammy Smith of conspiring to commit custodial interference earlier this year.
The Scottsdale woman planned to adopt baby Gabriel before he disappeared.
"I think things will become apparent at some time during the trial," said Victor.
In this case, Johnson's attorney said he won't dispute many of the facts, including a text message Johnson sent to the baby's father saying she killed the baby.
This is not a murder case. Johnson's attorney said the state has to prove its case.
"This case is not about whether or not she's innocent, this case is about whether or not the state presents evidence to prove beyond a reasonable doubt that she's guilty," said Victor.
Baby Gabriel would be 3-years-old. The trial is expected to last until November.
Follow this story: Prosecutor: Missing baby's mom upset over break-up