Illinois Attorney General Lisa Madigan filed a lawsuit Monday to stop a former Chicago police official convicted of lying about the torture of suspects from getting his $3,000-a-month pension.

Madigan's suit names Jon Burge and the Policemen's Annuity and Benefit Fund of Chicago, claiming that the board violated the state's pension code last month when it voted not to terminate Burge's benefits.

Burge was sentenced last month to 4 1/2 years in prison after being convicted in June of lying in a civil lawsuit when he said he'd never participated in or witnessed the physical abuse of suspects. A subsequent pension board vote on terminating Burge's pension failed by one vote, 4-4. It needed five votes to pass.

The four board members who voted to allow Burge to keep the pension said his convictions for perjury and obstruction of justice weren't directly related to his job as a police officer and that he didn't have any law enforcement duties when he was accused of making the false statements in 2003.