MACON, Ga. (WJBF) — A Georgia mother will spend time in jail for the murder of her three-month-old son.

ABC affiliate WGXA reports that Rebecca Kipp pled guilty to the second-degree murder of her child before the case could go to trial. She was sentenced to 20 years, with at least 12 years to be served in prison.

The child was reportedly found face down on a sofa, more than 3 1/2 hours after Kipp said she placed him there. Kipp admitted to investigators that she was “frustrated” with the boy and put him there while she went to sleep.

Kipp initially lied to investigators about how the child died, giving them multiple conflicting stories before finally confessing. Despite this, District Attorney Anita Howard told local news outlets that the evidence always supported negligent homicide.