Natasha McShane in happier times, before the 2010 baseball bat Bucktown beating

Heriberto Viramontes found guilty on all charges in Natasha McShane attack (VIDEO)

They had spent the night dancing. Natasha McShane was an exchange student from Northern Ireland studying urban development at the University of Illinois in Chicago, and she was delighted to hear she had just won an internship that allowed her to extend her stay.

Her friend Stacy Jurich had reason to celebrate too. She had just closed on what she called a “significant deal” for the financial services company that she worked for. They were both just 24. The future lay before them and it looked bright.

Then at 3 a.m. on April 23, 2010 the happy pair left The Tavern, a popular local bar, and began walking back to Jurich’s apartment. They didn’t know their lives were about to be turned upside down. They couldn’t have known what – and who – was waiting for them.

Under a Bucktown viaduct a baseball bat-wielding mugger attacked them. He hit them from behind, brutally hard, so hard they were on the ground bleeding and silent before they knew what hit them.

But what startles anyone reading about this story, what horrifies them most, is just how hard he hit them, how pitilessly. How does a man become so stunted and so cruel that he can hurt other people so badly for so comparatively little in return?

We now know the details of what happened, and we know that the alleged attacker Heriberto Verimontes, 33, is facing 25 felony counts, including armed robbery and attempted murder.

We also know that McShane spent weeks in rehabilitation in the U.S. before she was eventually returned to Ireland. There, she is confined to a wheelchair, unable to speak at all and requiring round-the-clock care.

It’s what we don’t know and may never that really haunts us. What can we make of Verimontes' pointless act?

The truth is the thing that scares us most about men like him: how they can hurt innocent people so badly; how they can injure them to the point of death without a second thought. He wanted their handbags, but he also wanted to seriously wound or kill them.

The first part doesn’t necessarily lead to the second, so what was wrong with him?

In that badly lit viaduct the two girls’ world of ambition and ever brightening prospects came face to face with a much darker world of drugs, criminality and inexplicable violence.

These two worlds do not often talk to each other. When they encounter, it usually means bad things.

It’s true that poverty is itself a form of violence. Long exposure to extremes of poverty can retard your view of the world completely. You live outside of the circle of ease and comfort. You cannot see past your next impulse or your next meal.

The Irish know there is a great deal to be said about the insidious way generational and ethnic poverty can stymie the progress of a people.

But what Verimontes did suggests an inner fury and contempt that has surpassed social and economic pressures and ventured into sociopathy. And that contempt for human life can be contagious.

Verimontes’ stripper girlfriend Marcy Cruz, 28, allegedly waited in a van while he brutalized the two girls. When he returned he told her that they had been “really pretty” and that he had done some “bogus s***.”

She knew what he had done, but she took the stolen Blackberry he gave her without a word and then they ran up bills together on the girl’s credit cards.

We know, roughly, what went through Verimontes' head. He told himself he wanted money. He decided to attack, and possibly kill, the two girls and take their money from them.

It would be easy, he thought. He decided to hit them with a baseball bat. Then he would be able to buy what he wanted.

So he decided to do it. He told Cruz it wouldn’t take long. By the time she had listened to one song on the radio he returned with the purses. Simple as that.

When McShane’s mother Sheila talks about her daughter she sometimes slips into the past tense now. It’s because there’s such a terrible gulf between who Natasha was and what’s been done to her.

In the middle of that gulf stands Heriberto Verimontes. On either side of him is silence.