Corrections & Clarifications: An earlier version of this story incorrectly stated the number of women murdered in Ecatepec. Ecatepec had 203.
ECATEPEC, Mexico — It's not hard to tell when you are leaving the relative safety of Mexico City and entering this violence-torn, crime-ridden suburb in the neighboring state of Mexico.
A metal cross marks the spot where the body of murdered woman was thrown on the side of the road leading into the sprawling-hillside slums, among the poorest, most densely populated and dangerous in Mexico.
And then a second cross. And a third.
They are grim reminders of the killings, particularly of women, that have terrified residents here.
On Sunday, just hours before Pope Francis would celebrate Mass before hundreds of thousands of people in another part of the city, a layer of choking smog hung over the municipality at dawn.
"This is the gateway to hell," said Manuel Amador, as he drove past the crosses.
The 40-year-old Mexico City resident and human-rights activist has taught high school for the past nine years in one of the suburb's most violent neighborhoods, Colonia Hank Gonzalez.
Amador agreed to show visitors around the day that the pope spoke at the Ecatepec Study Center.
During his homily, the pope denounced "the three temptations" of wealth, vanity and pride, and alluded to the drug lords that have controlled the city in recent years.
But the pope did not venture into Ecatepec's neighborhoods to see the conditions for himself.
Afraid to go anywhere but work
Earlier Sunday morning, a woman stood by a hillside road waiting for a ride to work.
Nearby, packs of stray dogs poked through heaps of trash in search of scraps of food.
When Amador and the visitors parked on the opposite side of the road and approached on foot, the woman turned and walked briskly away down the hill.
After being convinced that Amador and the visitors were not a threat, the woman said she was afraid she was about to be attacked.
The woman, 28-year-old Maria Garcia, said she came from Veracruz six months ago to live with relatives in Ecatepec, which is about the size of Phoenix. Many of the city's estimated 1.6 million residents are migrants who fled poverty in other states in search of better opportunities near the nation's capital, Mexico City.
But now she wants to go back because she does not feel safe, especially after dark, when assaults, kidnappings and robberies are common. She works at a tortilla factory about a 20-minute walk from her home. As she spoke, her hand trembled violently inside the pocket of her sweater.
"I go from my house to my work and that's it," Garcia said.
'How great that he has come'
Across the road, a row of shacks lined the street, indicative of a municipality where more than 100,000 residents live in extreme poverty, according to a 2010 report by the National Council for the Evaluation of Social Development Policy in Mexico.
Answering a knock on the door, an elderly woman pulled open a wooden gate a few inches and peered out, revealing a head of knotted gray hair.
Selerina Guadalupe Villa, 85, then invited the visitors inside.
She said she was originally from the southern state of Oaxaca and had lived in Ecatepec for 10 years.
Her house was constructed from old wood planks, covered by a corrugated metal roof. There was no running water, no electricity, no bathroom and only a dirt floor.
To keep warm in the early morning cold, the woman wore two thick sweaters layered on top of each other. To bathe, the woman said she used a bucket of water.
There were two simple beds, one for her and one for her 75-year-old brother, Agripino. Moments earlier, he had shuffled outside, wearing a dirty hat and clothing that looked like it had not been washed in months, on his way to sell scrap wood at the market. He hacked violently as he made his way up the road.
Clutching a cup of coffee she had just brewed on a tiny gas stove, Villa said she had heard that Pope Francis was going to celebrate Mass in Ecatepec later that day.
"How great that he has come," Villa said, seated on her bed, her knees shaking in the cold, "and to see the poverty that we live with here."
'We rarely see police here'
At an outdoor market, state police officers wearing florescent colored vests stood guard on street corners.
The police officers were for purely for show, deployed there in anticipation of the pope's visit, said Diego Antonio Garcia Tapia, 39.
"We rarely see police here," Garcia Tapia said. He and his wife, Ana Maria Mojica, 37, have a business selling fresh vegetables at the market. Garcia Tapia is also president of the association that oversees the market.
The couple said people live in constant fear because of the gangs that control the various Ecatepec neighborhoods.
A year ago, the couple became one of the victims.
While driving with a load of vegetables in their truck, four young men in a pickup blocked their way, got out, and pointed a pistol at Garcia's head.
They stole his truck, 20,000 pesos in cash (about $1,050 U.S.), and the vegetables.
They reported the attack to police, but nothing happened.
"They took a report, that's all that happened," Garcia Tapia said.
At another stall, a woman sold statues of Santa Muerte, Saint Death.
The saint has become popular with criminals who believe worshiping her will protect them from death.
The river of death
A short while later, Amador, the high-school teacher, climbed out of a taxi and walked down to the banks of the Rio de los Remedios, the water way that cuts through parts of Ecatepec.
The stench of raw sewage permeated the air, and laying in the muck down below was a life-sized doll. From a distance, the doll resembled the body of a naked woman, arms and legs stretched in the air.
It was a potent reminder of what the river has become, a popular dumping ground for the bodies of murder victims, most of them women.
Between 2012 and 2015, 1,715 women have been killed in the state of Mexico, often after being raped and mutilated, said Alejandro Melgoza, citing government statistics. Ecatepec is the municipality that had the highest number, with 203. Melgoza is a journalist who has written extensively about crime and "femicides" in Ecatepec for Proceso, a news magazine, and other publications.
In July, under pressure from human-rights activists, the government issued a "gender violence alert" to warn the public that women are being systematically targeted and murdered in Ecatepec.
However, the killings have continued, Melgoza said.
Since then, over 50 more women have been killed, he said.
Amador said he hopes the pope's visit to Ecatepec will focus attention on the poverty, crime and violence taking place there, especially the femicides, and force the government and police to take action.
The killings continue, Amador said, because criminals know they operate "with impunity."
Follow Daniel González on Twitter: @azdangonzalez