The Cook County State's Attorney's Office announced a first-degree murder charge against 30-year-old Thomas Tansey on Wednesday.
Tansey is accused of fatally stabbing 23-year-old Kenneth Paterimos outside Richard's Bar in the 400 block of North Milwaukee Avenue on February 21, prosecutors said.
Prosecutors said what started as a fist fight inside the West Town bar continued outside until Tansey allegedly pulled out a knife and stabbed Paterimos several times.
"The victim suffered stab wounds to the back of his head, his right ear, his middle back, right clavicle and right arm," said Cook County Assistant State's Attorney James Murphy.
WATCH: Sister of Richard's Bar stabbing victim speaks out
Prosecutors said the knife apparently severed an artery in Paterimos' arm, which proved fatal.
Police arrested Tansey a short time after the fight last month, but later released him before taking him back into custody Wednesday.
RELATED: Richard's Bar fatal stabbing suspect released without charges
His attorney said Tansey was the one who was attacked, and he was defending himself.
Family and friends of Paterimos held a vigil outside Richard's Bar earlier this week, demanding Tansey be arrested.
They left the courtroom Thursday without comment.
RELATED: 'Let us in!': Tensions run high at vigil for Richard's Bar stabbing victim in River West, suspect still not in custody
Tansey's attorney said he's a Marine veteran who served two tours in Afghanistan and suffers from post-traumatic stress disorder.
Despite earlier reports, attorneys on both sides said there's no evidence that the fight started over homophobic slurs.
"This did not have anything to do with any kind of slurs against anybody," said defense attorney Sam Amirante. "This was a fight in a bar."
The judge noted that Tansey has a previous conviction for a road rage-related incident that also involved a weapon.
Tansey's attorney said he will ask the judge to establish a bond when they go to court later this month.