CALGARY -- The notorious sex offender who kidnapped an 11-year-old girl from Deerfoot Mall has agreed to be designated a dangerous offender, court heard Monday.

But John Francis Dionne will avoid an indefinite prison term, as the Crown and defence lawyers have agreed to argue for a set sentence instead.

Crown attorney Gord Haight told provincial court Judge Allan Fradsham that he and defence counsel Allan Fay will present a joint submission to have Dionne ruled a dangerous offender.

"The Crown and defence are going to be seeking a dangerous offender designation followed by a long-term supervision order," Haight said.

"And, of course, that will be on top of whatever sentence the accused is given."

Under recent amendments to the Criminal Code, courts can find an offender to be dangerous, but still hand down a determinate sentence.

Prior to the changes, judges who felt offenders were treatable would simply designate them as long-term offenders and give them a specific sentence.

Outside court, both Haight and Fay said having Dionne declared a dangerous offender will have an impact should he commit further serious crimes down the road.

"The difference is if this order is granted and he reoffends in a significant way, he is already designated a dangerous offender," Haight said.

In that case the Crown would not have to go through the process of seeking a dangerous offender finding and could then ask for an indeterminate prison term.

Fay said the propose deal will give Dionne an opportunity to avoid a life behind bars.

"It's sort of going to give him a chance to demonstrate ... that he's making some changes," Fay said.

Dionne pleaded guilty in April 2011 to kidnapping an 11-year-old girl from Deerfoot Mall and driving her to Airdrie, AB.

Posing as a police officer investigating a shoplifting, Dionne escorted the child from the mall to his truck.

He dropped her off and an Airdrie fast food restaurant after he'd been stopped speeding by an RCMP officer who was unaware of the abduction.

Dionne told the girl not to talk during the traffic stop and dropped her off after getting his ticket.

He remains in custody pending his sentencing hearing, which begins June 11.