A South Florida man has been sentenced to life in prison for fatally stabbing his former underage girlfriend. A Broward County judge sentenced 40-year-old Alfredo Oliveira Friday. He pleaded guilty last month to second-degree murder. Officials say 17-year-old Jackline De Melo was stabbed 32 times in December 2006. Authorities say Oliveira actually used two different knives because the first one broke halfway through. According to the South Florida Sun Sentinel, Oliveira gave De Melo a place to stay after the girl ran away from her family. She was 16 at the time, but Oliveira claims she told him she was older. Oliveira's defense attorney portrayed him as a struggling Christian who knew the right path but snapped when De Melo told him they had no future and insulted him.