LAKE STEVENS, Wash. —  A woman was charged with manslaughter in the death of her 4-month-old son after she told authorities she taped a pacifier to his mouth to keep it from falling out.

Bonnie M. Desmond, 19, was charged Tuesday in the death of Noah James Petersen. Bail was set at $500,000.

Desmond called 911 Monday and said her baby was unconscious, but paramedics found the boy had been dead for hours, Fire District 8 Deputy Chief David Lingenfelter said. Prosecutors wrote in reports that Desmond later indicated a pacifier had been taped to the child's mouth but she had removed it before calling authorities.

"The only thing I can think of is I taped the pacifier to keep it from falling out. I didn't know it would hurt him, or I wouldn't have done that," Desmond told police, according to the reports.

No other children live in the home, which she shares with her fiance, and the fiance was not under investigation, said police Cmdr. Dan Lorentzen. The autopsy results were not immediately released.

If convicted, Desmond faces 6 1/2 to 8 1/2 years in prison, Snohomish County Deputy Prosecutor Mark Roe said.