CHICAGO (STMW) — A federal judge who dressed up as a nun in his downtown chambers Wednesday said donning the disguise helped him find a 25-year-old woman guilty of bank robbery.

Judge Matthew Kennelly wore the nun costume to test out Navahcia Edwards’ defense that the May 2011 heist of a TCF Bank she worked at in south suburban Palos Heights was in fact carried out by a white robber, not an African-American like her.

His verdict on what he dubbed her “reverse Al Jolson argument”?

“It’s not plausible.”

The judge’s actions at the end of a three-day bench trial might sound absurd, but Kennelly said he had a clear purpose.

Though prosecutors said Edwards and her fiance, Lyndon Germel Wesley, dressed as aged white nuns to rob the bank, pointing to the testimony of two tellers who said they could see the robbers’ black skin through the eye holes of their nun masks, Edwards’ attorney Charles Aron claimed that Wesley robbed the bank with a white accomplice.

Pointing to a frame of security camera footage in which the female robber’s unclothed arm appears to be white, Aron said a white robber had “blacked up” her face to confuse witnesses, referring to the Al Jolson minstrel movie “The Jazz Singer.”

But Kennelly wasn’t buying the claim that a white robber disguised herself as a black woman disguised as a white woman in a masterly double bluff.

He attributed the white appearance of the arm to “poor camera quality and lighting,” noting that Wesley, who confessed to the robbery, also appears to have a white arm in the security video, though he too is black.

“I put on the mask and looked in the mirror,” Kennelly said of his deliberations, adding that the white skin around his eyes was clearly visible through the mask’s eye-holes.

Edwards, who faces up to 25 years behind bars, showed no emotion as the verdict was announced.

She last year attempted to plead guilty while denying she was the robber inside the bank — an unusual request that Kennelly denied, leaving Aron an all-but impossible task in defending her.

The judge said that the overwhelming evidence of Edwards’ involvement in the build-up to and aftermath of the heist was enough to convict her, even if he hadn’t been convinced she carried it out.

Referring to Edwards’ purchase of the nun masks at an online costume store, he said: “The only conceivable purpose for purchasing nun masks and robes was to do something nefarious with them — let’s just say it was nowhere near Halloween.”

(Source: Sun-Times Media Wire © Chicago Sun-Times 2013. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)