A western Pennsylvania woman will spend 10 to 20 years in prison for drowning her 2-year-old son in a shallow creek in 1976, a crime she still claims to not remember despite apologizing repeatedly for it at her sentencing.

"I'd like to say I'm very sorry for what I did, because I did do it, but I do not remember," Glenda Masciarelli, 54, said moments before Fayette County Judge Steve Leskinen sentenced her Friday.

Masciarelli pleaded no contest to third-degree murder in December for drowning Alfred Masciarelli Jr. on Sept. 26, 1976, during a Sunday afternoon walk in the woods.

At the time, Masciarelli told police a mysterious man came up from behind her and grabbed the boy, presumably drowning him in the creek about 40 miles southeast of Pittsburgh as she ran screaming to neighbors for help.

Leskinen ordered Masciarelli to receive mental health treatment in prison, but stressed the boy's age and the lack of proof that she was legally insane in imposing the sentence.

"A 2-year-old child can neither provoke nor defend himself from this kind of an attack," Leskinen said, noting that Masciarelli, meanwhile, "has been able to live many years, 32 1/2 years, in freedom."

Masciarelli was charged in November 2006 when a state trooper dusted off the case and questioned her again. The trooper got her to acknowledge that she made up the mystery man story even though Masciarelli has yet to describe how or why she killed the boy.

Adam Sedlock, a psychologist who has treated Masciarelli for the last year, was the only witness at the 30-minute sentencing hearing. He testified that she suffers from a "major depressive disorder" that is probably rooted in a traumatic experience that occurred before she turned 20 — but that she either cannot remember or will not discuss.

Masciarelli was 22 when she killed the boy. Sedlock said she also suffers from a lifelong seizure disorder that may contribute to her being unable to recall the crime, even as she acknowledges responsibility for it.

"You're not suggesting she was legally insane at the time this crime occurred?" Judge Leskinen asked. "No," the psychologist replied.

Masciarelli didn't comment as she was led from the courtroom in handcuffs. Dressed in denim pants and a pink, short-sleeved pullover, she held a windbreaker in her handcuffed hands to shield her face from a television news camera as she was led from the courtroom.

The man she has lived with for several years, who is not the dead boy's father, refused to identify himself or comment.

Third-degree murder now carries a maximum sentence of 20 to 40 years in prison. Sentencing guidelines, which didn't exist in 1976, suggested a sentence of six to 20 years in prison in this case, Leskinen said.

"Obviously, we're a little disappointed in the sentence, but from talking to Mrs. Ms. Masciarelli, we anticipated this could happen," said defense attorney Nicholas Timperio Jr.

Leskinen imposed the maximum penalty the crime carried in 1976 even though he would have been free to give her probation or a much shorter sentence under the law in effect at that time, Timperio said.

The defense attorney doesn't anticipate appealing and said Masciarelli, in one sense, welcomes the closure the sentencing brings.

Police doubted her story all along, but polygraph examinations at the time didn't determine if she was telling the truth and Masciarelli didn't budge from her story, as the case gathered dust and she got on with her life.

The boy's father divorced her shortly after he was killed. He had told police his wife imagined being stalked by a man with a knife, and that she likely made up the story about the mysterious abductor.

District Attorney Nancy Vernon said she has kept Masciarelli's ex-husband, Alfred Sr., abreast of the case but that he did not wish to attend the sentencing hearing. Whatever Masciarelli's mental state, she was legally sane and responsible for her actions, Vernon said.

"There's no evidence she's mentally ill, not evidence she's not competent, there's no evidence she's insane," Vernon said.