In the backroom of a grimy Mexico City market shop, selling black magic paraphenalia, a 'witch' named Lukzero Agakhan sat me on a low wooden stool. Just a foot in front of me was a statue of a skeleton dressed in monastic robes gripping a scythe, it's bare teeth contorted into a grim smile below the black hollows of its eye sockets. I was here to undergo an exorcism at the altar of this chilling idol.

Lukzero wore a gold and purple cap which she claimed allowed her to communicate with the powerful spirits which were present. I could feel her hot breath against my neck as she chanted softly directly into my ear in a strange language that sounded like an ancient Aztec dialect.

The witch told me to start praying to the figure for acceptance - as the room filled with acrid smoke from incense sticks held over a red candle.

Lukzero lit a cigar and drew deeply on it before blowing the heavy smoke directly into my face. It was then that things began to turn uncomfortable…

I had paid the equivalent of £10 for an 'exorcism' with a witch of the Santa Muerte - or Our Lady of Death - which is the fastest growing religion in the world, according to some experts.

It was born out of the Mexican criminal underworld, where the violent wars between rival drugs cartels has made the murder rate soar and the value of life plummet. Here criminals will unthinkingly take your life for less than the value of a new pair of shoes.

Followers began building shrines hidden in their homes to pray to her for protection, help and the 'gift' in this violent society of the chance to die a peaceful and 'holy' death without judgement.

The first Western exposure came in an episode of Breaking Bad, the hit series about Walter White, a teacher-turned meth dealer in New Mexico.

When twin brothers, the Cousins supposedly belonging to the brutal Sinaloa cartel, are sent to wipe out White, they are seen praying to a shrine covered with candles surrounding a statue of Santa Muerte. They crawl on their hands and knees to reach her altar and make offerings, just as her real-life adherents in Mexico City do.

But Santa Muerte cannot be dismissed as fiction, it's lure has become very real. The Santa Muerte cult now has an estimated ten million followers from Buenos Aires, Los Angeles to Japan and Australia.

The rate of its growth is staggering in the seventeen years since the first church was publicly established in Mexico's capital.

The exorcism which I was undergoing is said to help people filled with sadness or negativity; a shamanistic ritual which purport to purify the soul, ridding it of destructive spirits which have taken hold within.

Continuing the ritual, the witch put a block of quartz stone into my hand and handed me a bunch of strange smelling leaves and green branches that I didn't recognise.

I began to feel dizzy from the strong tobacco and the incense smoke as Lukzero began chanting again while she rang loud bells in my ear.

My hands began to sweat horribly and a terror rose up from within me. All I could see in front of me was the hooded skull smiling through the smoke. It looked as it if had come to life.

It's eyes began to blaze with fire, its grinning mouth began to move and its horrible teeth began to chatter. I was petrified, all I could do was concentrate on my breathing as the ritual became ever more intense.

The witch brought the branches and the incense up to cover my face and told me to breathe in deeply, and then to exhale hard - many times.

I felt myself entering a trance - I felt as if I had been drugged. My movements were slower and I felt it difficult to concentrate on my thoughts.

My mind was going haywire and my speech was slowed. She told me 'open your eyes very slowly and look at your enemies'.

The room was spinning as I looked around, and my back was sweating. I could feel the hot hands of the witch on my shoulders and the smiling hooded skull in front of me.

The witch placed a golden idol of the Santa Muerte in my hand and then took a large swig of tequila from a clear bottle. She spat the mouthful of tequila all over the arm and hand which was holding the figure.

She said I was to keep the figure and put it on a red string necklace to wear for protection. She warned me that I should take a lot of care over what I ask from Santa Muerte, as the witchcraft which she had performed to get rid of the evil spirits was very powerful.

'A lot of people pray to Santa Muerte for evil things to occur', Lukzero told me. 'I only pray for the health and wellbeing of my family, but many people come to the White Lady (another name for the skeletal idol) to ask for the suffering of others or for criminal activities to go smoothly'.

'She (Santa Muerte) doesn't distinguish between good and evil', she added. 'She will give you anything you ask her for, but you have to give something in return' - adherents to Santa Muerte offer her money, cigarettes and tequila.

'What you offer depends entirely on you. You have to make personal sacrifices', said Lukzero, 'if you love tequila more than anything else, then that's what you must offer.'

'You have to be very careful. If you receive from her but then you do not give what you promised, she will destroy you. She will take everything away from you.'

I left feeling far from purified.

Santa Muerte's practices are deeply rooted in catholicism - followers have mass, communion, use rosaries and the resemblance of Saint Death to the Virgin Mary is clear.

But it has links to Aztec beliefs too - the image of Our Lady of Death is not that far from that of Mictecacihuatl - the queen of the underworld.

The Vatican is very keen to distance itself from the cult, calling it 'sinister and infernal'.

'Even if this cult is bringing people disillusioned with religion closer to God, it still uses witchcraft and belief in dark magic in its ceremonies,' said Monsignor Enrique Glennie, the rector of the Virgin of Guadelupe Basilica in Mexico City, one of Latin America's most popular catholic pilgrimage sites. 'Santa Muerte does not represent Christian values'.

'The White Lady doesn't judge me for what I do', says Alejandro Herrera, who robs people at gunpoint throughout Mexico City.

Herrera was kneeling at the altar of the only public Church of Santa Muerte, founded seventeen years ago in Tepito, a barrio in northern Mexico City.

He had left lit cigars as offerings to a saint he claims has protected his criminal endeavours ever since he began trusting in her. He has a large tattoo of Santa Muerte on his leg, which reads 'thank you, my mother' around an image of the saint of death engulfed by fire.

'I pray to Santa Muerte for success in my crimes and to protect me from the police', he told MailOnline after spending fifteen minutes deep in prayer before the skeleton figure.

'Every time I have success I immediately come to give thanks; she knows how much I have earned'.

Jesús Malverde, also known as the 'Narco Saint' – a Robin Hood figure championed by members of Mexican drug cartels for success in their criminal endeavours - also has two altars within the complex.

Malverde, a moustachioed Mexican man dressed in cowboy clothing, is left dollar bills, tequila and live bullets as offerings.

'We pray to Santa Muerte for many things, but the most common is for a peaceful death', the church's priest Juan Carlos Ávila said.

'I'm not scared of death, but I am scared of how I'm going to die. We ask the White Lady that when our time comes that we might die a holy death, without pain or suffering'.

Monsignor Ávila was a criminal himself before becoming an adherent of the cult. While holding mass, he asked all those members of the congregation who had committed murder to raise their hands. He was the only member of the congregation to admit to having taken the life of another.

'My girl (as he refers to the skeletal idol) is the only one who truly knows death', he preached, 'she is the only one who can forgive our crimes'.

'The fact that one day you will die is the only thing you can be certain of; it does a lot to change how you live your life', said Guillermo Mendoza, a regular worshipper at the altar of Santa Muerte.

'One day we will all end up looking like she does'.

In addition to exorcisms, the church also holds sacrificial masses on the first day of each month, when pigeons and farm animals are slaughtered on the saint's altar.

Every Friday at midday sees a 'prisoner mass', when family members of individuals who are languishing in prison pray for Santa Muerte to 'release the locks' of their cells.

'If Santa Muerte has attracted a large following, many of whom are dedicated to crime and witchcraft, it is because she is not a judgmental saint', says Monsignor Ávila. 'She accepts you for who you are'.

Read the original story on the Daily Mail