The ex-girlfriend of convicted Babes in the Wood murderer Russell Bishop faces jail after being found guilty of lying over evidence in his 1987 trial.
Jennifer Johnson admitted she lied over a sweatshirt found near the scene.
The 55-year-old said she had no choice after being threatened by her partner, but she was found guilty of perjury and perverting the course of justice.
Bishop was cleared in 1987 and not convicted of killing Karen Hadaway and Nicola Fellows, both nine, until 2018.
Johnson is due to be sentenced at Lewes Crown Court on Wednesday. Mr Justice Fraser said a custodial sentence was inevitable.
The jury reached a majority decision after 12 hours of deliberation.
The jury was told Johnson had lied “prolifically” and “significantly undermined” the trial in 1987.
Johnson claimed she had acted under duress and “had no choice” but to lie during the trial more than 30 years ago.
Jurors heard Ms Johnson first told police a sweatshirt found near the scene belonged to Bishop, but later denied it in a witness statement and at his first trial.
Mr Justice Fraser said Johnson was “infatuated” with Bishop but the relationship had been “problematic”.
Karen and Nicola’s parents – Michelle and Lee Hadaway and Susan and Barrie Fellows – did not give up their fight for justice and in 1988 called on Sussex Police to reinvestigate the case.
After his acquittal, Bishop went on to attack a seven-year-old girl on the South Downs in 1990. She was kidnapped, sexually assaulted and left for dead.
Bishop was sentenced to life in prison.
He was finally convicted of the murders of Karen and Nicola in 2018 following a DNA breakthrough that linked the sweatshirt to the girls and his home.