(Portland, OR)  --  A Portland native is facing a possible 30 years behind bars after being found guilty of sexually exploiting children in his care.  A federal jury convicted 44-year-old Andrew Kowalczyk this week of repeatedly sexually abusing and exploiting three young girls.  Court documents show he was babysitting the girls when the abuse took place.  Police arrested him in Washington state in 2008 after finding hard drives full of child pornography inside his car during a traffic stop.