A cadre of murderers and rapists, several of whom victimized young girls, will be set free from North Carolina prisons this month after state courts agreed that a decades-old law defined life sentences as only 80 years long.

Dozens more inmates could be released in the coming months unless the state can figure out a legal recourse to keep them behind bars, officials said Thursday. Gov. Beverly Perdue called them "dangerous criminals" who have repeatedly been denied parole.

"I'm appalled that the state of North Carolina is being forced to release prisoners who have committed the most heinous of crimes, without any review of their cases," Perdue said in a statement.

One of the 20 inmates set for release, Bobby Bowden, had argued that a law adopted in 1974 clearly defined life sentences as just 80 years. The 60-year-old convicted murderer believed that the statute, combined with good conduct credits, means his life sentence is now complete.

The Court of Appeals sided with Bowden last year. North Carolina's Supreme Court rejected an appeal from the state earlier this month after a lawyer from the attorney general's office had argued that the 80-year figure was ambiguous and likely meant to determine when somebody would be eligible for parole.