While playing a low-level thug in this week’s theatrical gangster thriller “Absolution,” Liam Neeson remains a commanding figure able to rouse our sympathy.

He’s an ex-boxer who has spent the last 30 years as an enforcer, thief and errand boy for a Boston-area crime boss – until he suddenly finds himself falling apart.

“The idea is of an aging hitman who’s suffering from CTE — chronic traumatic encephalopathy,” Neeson, 72, explained in a Zoom interview. The incurable brain disorder is associated with people who’ve had repeated concussions, such as football players and boxers.

“I’ve encountered a couple of ice hockey players who suffered from this. A couple of ex-boxers in Ireland and England who suffered from this. And I just find it fascinating, to be honest.

“It’s a horrible brain disease. You may remember Aaron Hernandez, the (New England Patriots) football player. When he died, he was just riddled with this thing — and he was 27.”

That makes “Absolution” very personal. Growing up in Northern Ireland, Neeson began boxing when he was nine.

“Yeah, and the last time I was 16 or 17. I was a kid but I was still a boxer getting hit. Personally, I did identify with this film.

“I remember once getting slightly concussed in a boxing tournament. I was 15 and I remember the decision in the contest. It was just exhibition stuff. But when I came out, my trainer was saying, ‘Will? Go downstairs, get changed.’

“And I didn’t know what he meant! ‘Downstairs get changed’? It lasted maybe five, six minutes. Scary. It was a concussion, from taking maybe one too many clubs to the head. But it did make me empathize with these CTE people and especially this character.”

The original title on the film was simply “Thug” which tells you all you need to know about Neeson’s brutal enforcer.  But “Absolution” can refer to the Catholic sacrament of confession where sins are acknowledged and absolved.

“I so dislike the title,” Neeson said. “To me, it says Catholic and kind of gives away the whole last third of the film. I much prefer ‘Thug.’”

As the character’s condition worsens, he attempts a reconciliation with his only daughter, who despises him, and her boy, his grandson. There’s also guilt for his part in a sex-trafficking ring.

Neeson knew exactly what the look would be for this Irish elder.

“I thought he should have a moustache and sideburns. I would love to have sort of a ‘70s leather jacket. I tried to just allow him to be and trust the script.

“Without putting any big emphasis on certain bodily mannerisms and stuff. You know, right?”

“Absolution” opens in theaters Friday