Marcos, a 36 year old Mexican from Long Beach, California, was nine when he was recruited to his local gang. “I got jumped. Five guys from the neighbourhood got together. I was the youngest, so they whooped my ass for about 15 seconds,” he remembers.

“Then we got up and celebrated and they give you a gun and say’ OK, these guys are your enemy now.”

Soon, he had put that to the test, acquiring status by shooting a rival gang member in the head, but nine years later Marcos was handed a jail term which kept him behind bars in Pelican Bay supermax prison for 18 years.

Now he is a ‘trainee’ with LA’s Homeboy Industries, a collection of social enterprises which employ and rehabilitate former gang members.

For men like Marcos, the scheme offers an alternative version of manhood, according to researcher Professor Ross Deuchar – for criminals who have only found family and role models in the gangs.

Marcos acknowledges this now himself “I was basically looking for family, looking for some type of father-figure, you know? And then my older ‘homies’ were father figures,” he says.

Marcos features in a new book by Mr Deuchar, professor of Criminology and Criminal Justice at the University of the West of Scotland, highlighting the way Homeboy Industries and similar schemes on three continents are using spiritual approaches to reform gang members and offer them an alternative kind of masculinity.

The book also looks at work with biker gangs in Denmark, incorporating programmes based on yoga and breathing exercises, and a Christianity-based initiative with former triad members in Hong Kong.

Gangs And Spirituality - a Global Perspective - is being launched at an event at the Scottish Parliament on Wednesday, when Deuchar will discuss the Danish model and call for the Scottish Government to do more to promote such approaches in Scotland.

Street and Arrow, a food-truck business based on Homeboy Industries has already been established in Glasgow, but Scottish recidivism schemes tend to shy away from the spiritual, he says.

Yet the evidence is that participation in such programmes can change the lives of participants and give them a new way of thinking about manhood, he says. His book offers “new insights about how the Scottish justice system can learn from the approaches used in Denmark”.

While the Hong Kong scheme is Christian and Homeboy Industries was founded by a Jesuit priest, acts of faith are not critical, he argues. “Religion is a system of worship and tradition but spirituality means different things to different people.

“For the older guys it was about having a language and framework for change. But they described it as almost a religious, spiritual experience, healing from the lifestyles and addictions they’d developed.”

Crucially, all the groups he studied acted as an alternative to the ‘family’ of the gangs.

“It almost gives them a new kind of fellowship. Homeboy Industries is very much about love, kinship and community building.

“Denmark is an increasingly secular society like our own, and religion is not seen as much more palatable, but meditation and breathing can be very powerful.”

Seeing members of dangerous Danish biker gangs using Yoga to move away from dependency on drugs or violence was as impressive as it was counterintuitive, he says. But he was struck by the importance of ideas of what a ‘strong’ man was to very many participants.

“”What if found with these groups all around the world was that as well as abuse and trauma in their background, they had this very toxic perception of what masculinity is about. These approaches let them deconstruct such narratives of violence, aggression and dominance. It is an approach we really need to become more open to.”