Juana Barraza targeted women over the age of 70, authorities said.
She was called "The Little Old Lady Killer," and she may be responsible for the murders of more than 30 women, all of them over the age of 70, according to authorities.
Juana Barraza, now 61, terrorized senior females in Mexico City as a serial killer who strangled women with a stethoscope. She was sentenced to 759 years in prison in 2015, convicted of killing 16 women.
"This was the first time in Mexican history that police" named a serial killer, according to author Susana Vargas Cervantes, who wrote "The Little Old Lady Killer," a book chronicling the murders, which investigators at first believed were committed by a man.
Later, they suspected the killer was a transvestite because witnesses described a large, muscular person wearing what appeared to be a wig and women's clothes. "They couldn't conceptualize of a female serial killer," Cervantes said of police.
"So they went in October of 2005 and arrested many transvestite sex workers and and after none of them matched their fingerprints, they concluded, OK, it's not a transvestite, but we're sure it's a transgender person," Cervantes recounted.
But the police were mistaken. They got a break in the case in 2006. A tenant returning home saw his landlady's corpse on the ground and a woman running away. She was arrested and word spread that Mataviejitas ("Little Old Lady Killer") had been caught.
After Barraza's arrest, the media had a field day with the fact she was also a fanatical participant in "lucha libre," Mexican masked wrestling. Her pseudonym was "La Dama del Silencio," the Lady of Silence.
From there, she became a celebrity of sorts. Songs were written about her case. Books were written. She was "a perfect sensational story," Cervantes said.
Her sentence of 759 years was the "largest one for any murder in Mexico City," Cervantes said.
Criminologists working her case said Barraza had been given away at age 13 by her alcoholic mother and became the victim of rape and abuse from her new guardian. She targeted women who would have been around the same age as her mom, officials said.