AN elementary school teacher has been jailed for 40 years for having sex with a 14-year-old student.

Shannon Alicia Schmieder, 39, will have to serve 20 years in the toughest sentence ever handed out by a US court to a teacher accused of underage sex, the Daily Mail reported.

The jail term compares with one for manslaughter and other serious crimes, legal experts said.

It has been reported the teacher's aide knew the child since he was born and was like a mother-figure to him before the relationship developed.

His distraught mother made an impact statement to the court, saying: 'She was a close family friend. We had gone to the same church together for 10 years. Our children were friends. Our families were friends. We did everything together. It's impossible to describe how we felt to find out this was going on.'

The newspaper reports the boy's parents became concerned when they noticed a change in the relationship between their son and Ms Schmieder. When they viewed their son's Facebook page it became clear something was wrong.

The mother said: 'Never in a million years did I think I would find what I thought was evidence of inappropriate behavior between them. But there it was.'

The sentence was handed out after the mother of the young victim spoke of her 'heartache and betrayal' at the loss of innocence of her son and that she struggles daily with what went on.

"We were told by investigators that our 14-year-old was a victim of child molestation. This was horrifying and unbelievable. I prayed that this was not true," she said.

"The more evidence that came out the truth became real, and I began to deal with grief, denial, guilt and so many other emotions.

"During this time I still was trying to maintain being a wife and mother. How could I have missed this... what mother can't protect her child? I trusted so much and believed that this friend was a gift from God.

"Words can't begin to explain the heartache we've experienced this past year and the betrayal we've endured. Messages that were recovered showed me more and more evidence and it became a living nightmare. I couldn't bear the thought of my boy trusting someone that had clearly manipulated him."