Denise Fergus also criticized the Parole Board for not telling her that Jon Venables was free until after he was released, The Daily Telegraph reported Tuesday.
Venables, 31, was released last week after serving just more than three years for child pornography crimes he committed after he was released from jail in 2001.
He previously served eight years for killing James Bulger in 1993.
Fergus, who said she learned of Venables' release Monday, told The Sun, "He is a danger to the public. He lies for his own sick ends."
She said she was told terms of Venables' parole included the condition that he not enter the county of Merseyside, where she lives.
"But the probation service didn't monitor him properly last time so I have no faith in their ability to do that now," Fergus said. "They should've kept him locked up for a long time."
Venables and Robert Thompson were both 10 years old when they abducted, tortured and killed James in Bootle, Merseyside, in 1993. Both were given new identities so they can live secretly in the community.
Ralph Bulger, James' father, called the decision to release Venables "disgraceful," the Telegraph said
"As ever, Venables is treated with kid gloves while James' family is treated as if we don't matter," Bulger said.
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