Soham murder trial judge Mr Justice Moses told Maxine Carr that the gravity of her offence reflected the gravity of the offences for which she gave a false alibi.
He told her: "You had plenty of opportunity to refuse to persist in a course of lying and deception. You chose not to.
"Your intelligence and strength of mind could have been used to ease the suffering of those families, but they were used to compound their misery.
"If you had had the slightest true regard for those girls or their families, you would have told the truth and the detection of your partner might have been more readily achieved.
"Your selfish concern for yourself and Huntley led you to lie all too readily, and all too glibly.
"You have lost the chance to mitigate the offence by failure to plead guilty in the face of overwhelming evidence.
"I take into account good character and time spent awaiting trial, but the least sentence of imprisonment I can pass consistent with my duty is three years six months.
"You will serve half of that and remain on licence for the rest. The time you have spent in custody will be taken into account. That is all I have to say." Earlier, in mitigation, barrister Mr Michael Hubbard said on Carr's behalf that she had already served 16 months, which was the equivalent of a two years and eight months prison sentence.
He said: "She faces an unenviable future and I really cannot say more than that.
"She is going to be blighted for years," he added.
