Canadian singer Justin Bieber performs during a concert at the Zocalo square, in Mexico City, on June 11, 2012. (RONALDO SCHEMIDT/AFP)

SUDBURY, ONT. - Police say an Alabama man who is awaiting sentencing for 23 offences pretended to be singer Justin Bieber and promised backstage passes to a 13-year-old local girl if she exposed herself to him on a webcam.

The city's police force became involved in the investigation in November.

Det. Sgt. Tim Burtt said an investigator identified the suspect as Christopher Patrick Gunn, 32, of Montgomery, Ala., and contacted American authorities at the FBI and the Department of Homeland Security this summer.

"They had actually already arrested the gentleman down in Alabama at that time, because he had been doing the same thing there," Burtt said.

Police allege Gunn used various Internet chat rooms and social media to threaten hundreds of girls aged 9-16.

The Department of Homeland Security says Gunn pleaded guilty on Aug. 22 to two counts of possession of child pornography, 14 counts of interstate extortion and seven counts of stalking.

He is scheduled to be sentenced in Montgomery on Nov. 20.

None of those charges stem from the case involving the Sudbury teen.

"Essentially, what's happened is discussions are going on with our investigators and the U.S. authorities on whether additional charges will be laid," Burtt said.