On Oct. 21, a body was found off a county road west of Corpus Christi, Tex., with bullet wounds to the chest, abdomen and shoulders.

The victim was Stephanie Montez, a transgender woman. But because the police misidentified her as a man, it was not until last week that Ms. Montez, 47, was known to be among the more than two dozen transgender Americans killed this year.

Even as transgender people have scored political victories and turned public opinion in favor of more protections, violence has risen, especially against black and Hispanic transgender women. And Ms. Montez’s case shows the difficulties advocates face in tracking killings and other hate crimes.