A brother of "The Dark Knight" director Christopher Nolan was allegedly plotting a Batman-like escape from a Chicago federal prison where he was being held while fighting extradition to Costa Rica on murder charges.

Matthew Nolan, 41, a longtime Chicago resident who sometimes bragged he was a member of British special forces, was charged last month with making and possessing 31 feet of rope, a harness and other prohibited items "designed and intended to be used to facilitate an escape" from the Metropolitan Correctional Center.

Prison authorities discovered the contraband while searching Nolan's cell a few weeks after his arrest in the extradition case, sources said.

"It is clear from the items seized ... that Nolan had devoted a significant amount of time during his first two weeks at the MCC preparing for an escape," prosecutors said in a filing in a related case.

Authorities also found that Nolan had made a metal clip from a pen that was able to unlock handcuffs. But a source said it was unlikely that Nolan could have escaped from the high-rise prison in downtown Chicago.

A Bureau of Prisons spokeswoman said its records show no one has ever escaped from the jail where gang leaders, mobsters and higher-level drug dealers are held while awaiting trial in nearby federal court.