LAKELAND, Fla. (CBS Tampa) — A teenage girl is accused of choking to death her newborn son while the umbilical cord was still attached.

Cassidy Goodson, a 14-year-old student at Kathleen High School, has been charged with premeditated first degree murder and aggravated child abuse in her son’s death last month.

Polk County authorities say that Cassidy gave birth on Sept. 19 in her bathroom’s toilet, even using a pair of scissors to “pry out” the 9.5-pound boy.

“Cassidy lifted the moving infant from the toilet, felt for a pulse, found one, then placed her hands around the infant’s neck and squeezed until he wasn’t moving or breathing any longer,” the Polk County Sheriff’s Office statement said. “She took the infant’s pulse again and found none.”

Authorities were shocked at the nature of the crime.

“Her son was still connected to her by the umbilical cord when she choked him to death,” Polk County Sheriff Grady Judd told The Ledger. “I just can’t get over that.”

Deputies said in the statement that they were called to the Lakeland house after Cassidy’s mom, Teresa Goodson, found the full-term baby inside a shoebox in her daughter’s room.

Cassidy, who concealed her pregnancy from family by wearing baggy clothes, allegedly told authorities that she choked her newborn son to “stop him from breathing.” He died as a result from asphyxia from strangulation and blunt force trauma.

Family members told authorities that they believed Cassidy was pregnant but Teresa Goodson kept denying her daughter was pregnant, saying that pregnancy tests showed no positive results.

“She was in complete denial,” Judd told The Ledger.

Cassidy is currently being held at the Polk County Juvenile Detention Facility.