SIOUX FALLS, S.D. (KELO) — A 20-year-old Sioux Falls woman is facing manslaughter and abuse charges after her baby died.

According to police, Ashlynn Swenson-Marshall left her two-month-old baby unattended in a bathtub at a Sioux Falls apartment. She told investigators when she came back in the room, she found the baby face down in the tub.

She called for help and her sister-in-law performed CPR.

Investigators describe the mother as “visibly shaking, crying and breathing at a rapid pace.”

Efforts to revive the infant failed and the baby brought to the hospital, where he died three days later.

While the baby died in July, prosecutors decided to file charges about a month later after taking a closer look at the results of the police investigation.

Police arrested Swenson-Marshall Sunday morning. Police say it was the time factor that probably played a role in the manslaughter charge.

“So this wasn’t just a matter of seconds that she left. I don’t know if we have the exact time frame that she left that infant unattended but it may have been anywhere from seven to ten minutes. I think that’s according to the affidavit so that probably one of the bigger factors,” Sioux Falls Police Public Information Officer Sam Clemens said.

The criminal complaint infers Swenson-Marshall was “reckless” in the baby’s death.

The autopsy report says the cause of death was an Anoxic brain injury due to drowning. Anoxic brain injuries are caused by a complete lack of oxygen to the brain, which results in the death of brain cells.