DHAKA, Bangladesh — In an alleyway off a marketplace specializing in meat and live chickens, up a few narrow, precipitous flights of cement stairs, can be found the most sought-after transgender crime fighter in Bangladesh.

Reporters from newspapers and television stations are combing Dhaka looking for her, and so are police officials, who said they would like to give her an award for bravery. But since Monday, when she nabbed two suspects in the killing of a blogger, the woman, Labannya Hijra, 21 — who takes her last name from the South Asian term for biological males who identify as women — has melted back into the city where she has been invisible for so long.

After three days of searching, a reporter found her on Thursday, and she agreed to tell her story publicly for the first time. She was willing to speak only after her mentor, another hijra named Sapna Hijra, granted her permission.

The blogger, Oyasiqur Rhaman, 27, was attacked by three young men, who had reportedly been ordered to kill him for writing comments critical of Islam on social media. Ms. Hijra grabbed the T-shirts of the fleeing men, who were students. As they struggled in her grasp, a machete fell out of one man’s bag and clattered to the ground. One of the men whacked at her hand and shouted at her to let him go, and she yelled back, “Shut up!”