GULFPORT, Miss. –– A Mississippi gang member was sentenced Monday to 49 years in prison in the first federal hate-crime prosecution against the killer of a transgender person.

Joshua Vallum, 29, a member of the Latin Kings gang, pleaded guilty to fatally beating and stabbing 17-year-old Mercedes Williamson, whom he had dated. Vallum admitted that he killed Williamson because she was transgender and because he feared reprisal from other members of the gang, which forbids homosexual relationships.

The case marked the first time that federal prosecutors have used the 2009 Matthew Shepard and James Byrd Jr. Hate Crimes Prevention Act to charge someone for targeting a transgender victim, according to the Justice Department.

“Today’s sentencing reflects the importance of holding individuals accountable when they commit violent acts against transgender individuals,” Attorney General Jeff Sessions said in a statement. “The Justice Department will continue its efforts to vindicate the rights of those individuals who are affected by bias-motivated crimes.”

Vallum was previously sentenced to life in prison for the slaying under state charges in Mississippi, where Vallum stabbed Williamson and beat her with a hammer after driving her into the state from Alabama. Because Mississippi lacks hate crime legislation, Jackson County prosecutors sought the cooperation of federal authorities to see if such charges could be pursued.

The 2009 law, which President Barack Obama signed into law, expanded federal hate crime laws to include acts motivated by the victim’s real or perceived gender, gender identity, sexual orientation or disability. It is named for Shepard, a 21-year-old gay Wyoming man who was killed in 1998 after being beaten and tied to a fence, and for Byrd, a 49-year-old black man murdered in Texas that same year by white supremacists who dragged him behind their truck and decapitated him.

The sentence comes amid growing concern about violence against transgender people, particularly transgender women. At least 22 transgender people, most of them women of color, were killed in 2016, according to the Human Rights Campaign, an LGBT rights group. It also comes as groups have questioned the Trump administration’s commitment to LGBT rights.

Shortly after his confirmation, Sessions reversed course on Obama-era guidance requiring schools to let transgender students use restrooms and locker rooms that match their gender identities. Sessions also recently let stand a court order blocking an anti-discrimination provision in the Affordable Care Act that applied to transgender people. As a senator, Sessions opposed the Matthew Shepard act, which he said at the time inappropriately singles out a specific group for special protections.

According to the Justice Department, Vallum decided to kill Williamson after learning that a friend had discovered Williamson was transgender. In May 2015, Vallum drove to Williamson’s home in Alabama, lured her into his car, and drove her to his father’s home in Lucedale, Miss. While Williamson sat in the passenger seat, prosecutors said, Vallum used a stun gun to incapacitate Williamson and then stabbed her repeatedly with a 75th Ranger Regiment pocket knife.

Williamson tried to escape, prosecutors said, but Vallum chased her into the woods, where he repeatedly hit her in the head with a hammer.

When the Justice Department announced in December that Vallum had pleaded guilty to hate crime violations, LGBT rights groups lauded the department’s actions.

“The Department of Justice’s leadership on hate crimes prevention is essential for stemming the epidemic of violence facing the transgender community,” the Human Rights Campaign said in a statement. “We urge the incoming Trump administration to continue to enforce this important law and to commit to protecting the rights of LGBT Americans facing violence in their communities.”