(CNN) Jemel Roberson couldn't wait for his son's first Christmas.

With a 9-month-old boy and another baby on the way, the 26-year-old security guard was working extra shifts to buy gifts for his son and his child's mother, family attorney Lee Merritt said.

Jemel Roberson's son Tristan is now 9 months old.

During one of his shifts last weekend, a gunman started shooting up Manny's Blue Room, a bar in suburban Chicago. Witnesses said Roberson bravely stopped the shooter and pinned him to the ground.

But shortly later, a Midlothian police officer shot and killed the security guard, leaving the mother of their child in shambles.

"A family member called me and told me. ... I just broke down crying in the bathroom. For a long time, I was in the bathroom," said Avontae Boose, who's pregnant with the couple's second child.

Their 9-month-old son Tristan is too young to understand what happened. But he knows his father is missing.

"He's just been calling (for) his dad," Boose said Thursday.

Security guard Jemel Roberson, 26, wanted to become a police officer.

Many community members are demanding answers as to why Roberson was killed. One major point of contention is whether Roberson was wearing anything with "security" written on it.

While witnesses said the guard was wearing clothes that clearly identified him as "security," Illinois State Police, the agency now leading the investigation, said Roberson was wearing "plain black clothing with no markings readily identifying him as a Security Guard."

Witness Adam Harris told CNN affiliate WGN that Roberson "had somebody on the ground ... with his knee in back, with his gun in his back like, 'Don't move.' "

Merritt lauded Roberson as "the quintessential good guy with a gun" for stopping an active shooter. "But he still had to face the reality of being a black man in America," Merritt said.

Illinois State Police described the events differently.

"According to witness statements, the Midlothian Officer gave the armed subject multiple verbal commands to drop the gun and get on the ground before ultimately discharging his weapon and striking" the security guard, Illinois State Police said in a statement.

Midlothian Police Chief Daniel Delaney described the shooting as "the equivalent of a 'blue on blue,' friendly fire incident."

The Roberson family's attorney disagreed.

"If this was a case where they saw this as a friendly fire, as if a police officer was shot, then this would be handled much differently," Merritt said. "There would be more transparency."

Specifically, Merritt said authorities should identify the officer.

"It's important to put that name and face out in the public spectrum because it allows the community to report if this officer has a history of brutality," he said. "That information certainly becomes relevant for any future criminal proceedings."

Midlothian Police Chief Daniel Delaney has not identified the officer, but said he is a white male who has worked with the department for about four years. Per standard policy, the officer is on paid administrative leave pending the outcome of the state police investigation.

"What we have also learned is Jemel Roberson was a very brave man who was doing his best to end an active shooter situation at Manny's Blue Room," Delaney said in a statement Wednesday.

"The Midlothian Police Department is completely saddened by this tragic incident and we give our heartfelt condolences to Jemel, his mother, his entire family and his friends. There are no words that can be expressed as to the sorrow his family is dealing with."

Boose, now grappling with the reality of raising two children without their father, is already thinking about what she will tell her children about their dad.

"He was a good father. He was a hero," Boose said.

"I'm going to tell them when they get older -- when they get real older -- what happened to their father. That he was a hero, and he saved a lot of people."