A man has been sentenced to 49 years behind bars for the murder of a transgender woman in the US state of Mississippi.

Joshua Vallum was convicted of the 2015 killing of 17-year-old Mercedes Williamson, in first case prosecuted under the federal Hate Crimes Prevention Act involving an attack based on gender identity.

Vallum, a member of the Latin Kings gang, stabbed and beat Williamson to death after shocking her with a stun gun in 2015. The pair were having sex, and the prosecution alleged that Vallum killed Williamson in order to hide this fact from the anti-LGBT+ gang. The AP reports that ‘homosexual activity’ is forbidden in the Latin Kings.

He pleaded guilty to the federal crime in December, after previously pleading guilty to state charges.

U.S. District Judge Louis Guirola Jr. had the authority to sentence Vallum to life in prison, but a plea agreement was reached with his lawyer that took into account the abuse Vallum encountered as a child.

“Mr. Vallum lived through a childhood that was characterized by abandonment and neglect,” said Vallum’s public defender Ellen Allred. “It’s difficult to image how a mother could lock a two- or three-year-old child in a room for house on end while adults did drugs.”

Judge Guirola said during sentencing: “The taking of a human life because a person has a particular gender identity is particularly heinous and cannot be tolerated in an enlightened society.”

During sentencing, Vallum begged for forgiveness from Williamson’s family, none of whom were present. “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.”

US Attorney General Jeff Sessions responded to the case by saying: “Today’s sentencing reflects the importance of holding individuals accountable when they commit violent acts against transgender individuals.

“The Justice Department will continue its efforts to vindicate the rights of those individuals who are affected by bias motivated crimes.”

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