SACRAMENTO, Calif. -- A 33-year-old woman has been arrested after detectives said she intentionally drowned her baby boy in a toilet, the Sacramento County Sheriff's Department said.

Kristen Gibson was under investigation after deputies went to the 10000 block of Mills Tower Drive in Rancho Cordova to investigate an infant's death on July 9.

A female roommate told an emergency medical worker that she had found the woman and infant in the bathroom.

"The responding deputies' initial investigation revealed that the woman had given birth to the infant while on the toilet," the department said in a release.

However, detectives determined after an extensive investigation that Gibson had intentionally allowed her full-term, 8-pound baby boy to die.

The baby was born alive and intentionally drowned in the toilet after Gibson severed his umbilical cord, forensic analysis and an investigation by the Sacramento County Coroner's Office determined.

Gibson was arrested Thursday. She is being held without bail at the Sacramento County Main Jail and will be arraigned Monday.

She faces charges of homicide and assault resulting in the death of a child.