CALGARY -- A man whose offences against underage girls spanned almost 15 years has been declared a dangerous offender in a Lethbridge courtroom this week.

Trevor Pritchard, of Coaldale, Alta., was found guilty in January 2019 of sexual assault, luring and possession of child pornography.

His offences, that targeted underage girls, took place between 2003 and 2017.

Pritchard's most recent conviction resulted in a six-and-a-half-year sentence for sexually assaulting a 15-year-old girl he lured using a computer.

During the dangerous offender hearing, the Crown called nine witnesses and reviewed reams of documents that filled seven boxes, a large plastic tub, seven binders and stacks of folders and reports.

The sentencing judge told the court that the proceedings proved Pritchard preyed on underage girls and had a pattern of persistent and aggressive behaviour.

He also showed no remorse for his victims, the court heard.

A dangerous offender designation means Pritchard will be held in jail for an indefinite period of time.

He will need to engage in treatment, accept institutional support and take responsibility for his crimes before he is eligible for release.