Glasgow is at the centre of a ruthless trade in gangland misery.
A new crime study reveals hired thugs willing to attack for cash and gives and insight into how they operate and why they do it.
Researchers interviewed 65 ex-offenders in the west of Scotland and discovered that vulnerable people are often used to carry out violence.
They also uncovered multiple categories of 'enforcerers' used to settle underworld scores, the Sunday Mail reports.
These include "amateurs, dilettantes and journeymen" who were prone to flawed planning, increasing their chances of being caught.
One reformed gangster revealed he was paid £750 to ambush a target and slash his face as he returned home from work.
The criminal, who remained anonymous, said: "I waited in the bushes. I came up behind him before he put the key in the door, just tore the knife along his face. He was wrecked, didn't scream, nothing. So I plugged him in the back and bailed. I received £750."
Professor James Densley, an expert in criminal justice at Metropolitan State University, led the research team from the University of the West of Scotland and Birmingham City University.
Criminologists analysed a network of hardmen and women in gangs in Scotland and the Midlands. They found ex-soldiers and military personnel often made the most effective, dangerous enforcers due to their "violence proficiency".
Prof Densley said: "Underworld enforcement exists on a continuum both in terms of lethality and proficiency. Not all contracts are deadly hits and not all enforcers are created equal. Like most jobs, it's not what you know but who you know that matters to become an enforcer.
"High-status offenders who remain strongly embedded within offending networks as they age are well placed to make the transition from lower-level crime into contract enforcement.
"Glasgow has a long underworld history, organised crime is part of the fabric of the city. More people have exposure to enforcers and some practical experience of basic enforcement. It's less of a niche market. Barriers to entry are lower.
"Military experience creates opportunities to enter into enforcement because skills are transferable but also because service in the Armed Forces is a credible signal of certain intangible traits necessary for the job - like violence proficiency.
"In some cases, military ties also afforded access to firearms and other tools of the trade."
The study, entitled Who Are The Enforcers?, mentions notorious underworld figures Robert Dawes and the Lyons and Daniel crime clans.
The team also found Glasgow and Birmingham suffer "postcode" violence.
Prof Densley added: "Debt-bondage can be used to coerce people into organised crime, especially in Glasgow where levels of drug addiction and poverty are high."
