Kimberly Pappas, 26, was sentenced Monday to nine to 20 years in prison for stuffing her newborn son into a plastic bag after giving birth to him at her suburban Detroit workplace.

Pappas pleaded guilty to second-degree murder earlier this month, under an agreement with prosecutors to drop charges including felony murder and child abuse, according to the Associated Press.

Throughout the trial, Pappas said she expressed the indescribable pain and regret she felt for her actions.

"The pain and regret I have over this really can't be put into words," she said.

Paramedics testified that they found the body of the infant inside a plastic bag on March 31 inside Pappas' desk at CEVA logistics in Redford where she worked temporarily, according to ABC's Detroit affiliate WXYZ.

The infant, whose body was found with bruises on its head and lungs, was determined to have been alive for 20 to 30 minutes and died of asphyxiation. His death was ruled a homicide.

Pappas had previously denied her pregnancy, according to her sister and co-worker, Cassandra Pappas, The Detroit News reported. She reportedly never bought baby items for the family's home and didn't discuss her options, such as abortion or adoption.

Her father, James Pappas, said he and the rest of the family had "unconditional love" for her and will visit whenever they have the opportunity.

"Kimberly, we love you very much," he said. "We will support you with as many visits as we can."