Wrong Leads ..
Throughout the spree, authorities couldn't accurately identify Juana. Authorities were heavily criticized and called out for just merely doing a sweep through Mexico City's transvestite prostitute population. Officials also released information saying that there was two maniacs running around Mexico City murdering helpless old ladies. Witness statements were reported that the killer wore women's clothes to gain access into the homes. A "large women" in a red blouse was even seen leaving the house of one of the killer's victims. To add onto that, 2 months later police began to check the fingerprints of bodies in the city's morgue and were lead to apparent belief that "The Old Lady Killer" committed suicide.
Forensic Evidence
Juana kept her scenes very bloody yet clean of prints and evidence. Although she would sometimes leave the weapon she used to strangle the victims with. Majority of her killings were with a stethoscope that she wore almost as a trophy; She was arrested wearing it.
Deficiency & Lack of Technology ..
The kilings lasted for years; Authorities were looked at as a joke because even with small information and evidence found, not much was known about the killer. Most of this was because, at this time, Mexico was not well equipped with technology or forensic knowledge. Too many elderly women lost their lives because of it.