LGBTQ-rights advocates were asking Missouri prosecutors to consider the recent killing of a transgender teen as a hate crime.
Missouri is one of 17 states with hate crime laws covering gender identity. The 1998 murder of a gay college student in Wyoming inspired the federal law.
The Human Rights Campaign reported Ally Steinfeld was the 21st transgender person killed this year in the U.S.
"Hate crimes rend the fabric of our society and fragment communities because they target a whole group and not just the individual victim," Sarah Warbelow, the Human Rights Campaign's legal director, said.
Steinfeld, who was born as Joey, came out as transgender on Instagram June 13. She told her friends and family that she was pansexual, attracted to people without regard to gender or gender identity. Detectives say she was killed at a girlfriend's mobile home about three months later.
Steinfeld was homeless and living with friends after coming out. She was in the process of starting hormone treatment and wanted to undergo reassignment surgery. She had been dating Briana Calderas, 24, for about a week when she was killed.
Calderas' brother, Andrew Vrba, 18, told detectives he wanted to poison Steinfeld, but when he couldn't, he chose to stab her instead. He admitted to mutilating her genitals, gouging out her eyes and burning her body.
Detectives arrested Calderas, Vrba and Vrba's friend Isis Schauer with first-degree murder, abandonment of a corpse and armed criminal action. James Grigsby, who is accused of helping them to dispose of the body, faces abandonment of corpse and armed criminal action charges.