 Story highlights Joshua Vallum pleaded guilty to killing his ex-girlfriend 
 
 Justice Department: He killed because she was transgender 
 
 (CNN) A Mississippi man was sentenced to 49 years in prison Monday and fined $20,000 for killing his ex-girlfriend because she was transgender, the US Justice Department said. Joshua Vallum, 29, of Lucedale is the first person prosecuted for a federal hate crime in which the victim was targeted for being transgender, the Justice Department said in a news release. Merecedes Williamson 
 
 Vallum, a member of the Almighty Latin Kings and Queens Nation crime gang, feared reprisals from gang members if they found out about the relationship, the Justice Department said. Federal prosecutor Julia Gegenheimer had said at Vallum's plea hearing in December that he began planning to kill Williamson after a friend called him in May 2015 to say he'd discovered Williamson's identity. Vallum knew Mercedes Williamson was a transgender teenage girl when they began dating, but kept her gender identity secret, prosecutors said. Read his work at https://www.apnews.com/search/Jeff_Amy .
– A Mississippi man received a 49-year prison sentence Monday for the first-ever conviction on federal hate crime charges arising from the killing of a transgender woman, the AP reports. In a case watched by the LGBT community nationwide, US District Judge Louis Guirola Jr. sentenced Joshua Vallum, 29, in the 2015 killing of 17-year-old Mercedes Williamson. It was the first case prosecuted under the federal Hate Crimes Prevention Act involving a victim targeted because of gender identity. Prosecutors said Vallum shocked Williamson with a stun gun, stabbed her, and beat her to death to keep fellow Latin Kings gang members from discovering the two were having sex. Gang rules barred homosexual activity and declared it punishable by death. The couple had broken up in 2014 but a friend had recently discovered Williamson was transgender, per CNN. Guirola could have sentenced Vallum to life in prison, but heeded a lesser sentence suggested in a plea agreement between defense attorneys and prosecutors, citing Vallum's neglected childhood and other issues. Both the judge and defense lawyers said Vallum's history of abuse as a child had to be considered. Vallum pleaded guilty to the federal charges in December. He previously pleaded guilty to a state murder charge that led to a separate sentence of life without parole. On Monday, Vallum begged forgiveness from Williamson's family and friends, though none of them were present—only a few reporters, the judge, and Vallum's father and stepmother. "Every day, I live with the guilt and regret of my actions," Vallum said. "If I could bring back Mercedes by giving up my life, I would gladly do so."