AUBURN — A Lewiston man pleaded guilty Wednesday to manslaughter in the bathtub drowning of his 11-month-old son.

Sean St. Amand, 28, was sentenced to three years in jail with all but nine months of that term suspended, plus two years of probation.

Police said they responded to 125 Pierce St. for a 911 call reporting an unresponsive child on Oct. 20, 2014.

Police found Sean St. Amand II not breathing and administered CPR until ambulance crews arrived.

Police said they smelled a strong odor of burnt marijuana when they entered the apartment and saw drug paraphernalia on the kitchen table, Assistant Attorney General Deborah Cashman told a judge Wednesday in Androscoggin County Superior Court.

Police saw that the bathroom floor was covered with water.

Antonio Asphy, a house guest who said he had been in the apartment, told police he had been smoking marijuana with St. Amand in the kitchen while the baby and his nearly 2-year-old sister, Shay-Lynn, were in the bathtub with the water running, Cashman said.

Asphy told police that St. Amand would rise every couple of minutes to check on the children in the bathtub.

St. Amand had told police that he had left the children unattended in only 5 inches of bathtub water for only 13 seconds while he retrieved two towels. Cashman said St. Amand had also made statements to police that he had left the children for 2-3 minutes.

He also told police that the water on the bathroom floor was from the toilet overflowing.

The boy’s mother had told police she had warned St. Amand not to leave the two children unsupervised because of the girl’s “aggressive tendencies,” Cashman said.

A medical examiner who performed the autopsy on the boy determined that he had drowned and that he had bite marks on his back and arm.

Other witnesses would have testified at trial under oath that St. Amand had left the children alone for minutes at a time and that the bathtub had overflowed, Cashman said.

In all, Cashman said police estimated that the two children had been in the bathtub for roughly 45 minutes.

Androscoggin County Superior Court Justice MaryGay Kennedy told St. Amand that had he been convicted of manslaughter at trial, he “very likely could have received a harsher sentence.” The Class A crime is punishable by up to 30 years in prison.

He was ordered to complete parenting education courses.

“Mr. St. Amand, I’m very sorry for what happened,” Kennedy said.

His sentence was stayed until Jan. 2.

cwilliams@sunjournal.com