Nina Robertson wishes she could talk to her mom, who would know what to do.

After her brother, Chad Robertson, was fatally shot in the back by an Amtrak police officer in Chicago in February, it was Candice Hackett's strength that kept Nina and her siblings from slipping further into despair.

And so it was profoundly cruel that less than two months after Chad's death, Hackett, 45, would also fall victim to gun violence — this time in north Minneapolis — sending the vulnerable family into another tailspin of grief and anguish.

"It kind of felt unreal," said Nina, 28. "We were in a denial stage of grief and I think we didn't fully deal with what had happened and what was going on with Chad."

Now, as the family copes with the fallout of a second unexpected loss, they say they must stick together to see justice in both slayings. Robertson's death drew widespread community outrage, and LaRoyce Tankson, the officer who pulled the trigger, was charged with first-degree murder and awaits trial in Chicago. Meanwhile, investigators continue the search for Hackett's killer.

Amid the chaos, Nina said she has no time to grieve. Her brothers and sisters need her. She described trying to "create a space where these kids can have some sense of normalcy," while hiding her own sorrow.

"These kids literally do exactly what they see me do," she said. "I've been having to wear a damn mask around here."

But tears flow down her face when she recalls the day Chad, 25, was traveling Feb. 8 from a relative's funeral in Memphis, when his bus made a scheduled stop in downtown Chicago.

Prosecutors say Robertson and two friends ducked into Union Station to warm up when they were approached by Tankson and his partner, who asked them to leave after they were caught smoking marijuana. A few minutes later, they again encountered the officers near the station and a confrontation ensued.

Tankson "did not suspect Robertson [or his companions] of any criminal offense other than possession of cannabis nor did they witness them committing any other criminal offense," prosecutors said.

Nevertheless, Tankson and his partner started to frisk the pair.

Robertson took off running, and Tankson reportedly drew his handgun, dropped to one knee and fired a single shot at Robertson, who by then was about 75 to 100 feet away, authorities said. At least six people witnessed the incident, none of whom saw Robertson, who was unarmed, "gesture or turn" toward the officers as he fled, according to authorities.

Robertson died Feb. 14, triggering widespread protests from St. Paul to Chicago. Tankson was charged two days later.

'Exact same thing'

Hackett, who left behind 10 biological children and three stepchildren ages 8 to 27, was killed by crossfire outside a north Minneapolis biker bar on the morning of April 2 when a stray bullet struck her in the head. She died two days later, one of seven homicides so far this year in the city.

Police have a few leads in the case, but so far haven't publicly announced any arrests.

A recently filed search warrant affidavit revealed that Hackett's shooting likely resulted from a dispute between rival biker gangs.

Investigators also spoke with witnesses who reported seeing a woman firing several warning shots with a .380 handgun, the warrant said.

Relatives said that the shooting ripped open wounds that had just begun to heal after Chad's death.

One of Nina's sisters, LaNisha Taylor, 21, said the family was no stranger to death. Nisha, as she's known to family, says she is at various stages of mourning for her mother, brother and boyfriend, who died in 2016, almost a year to the day that Robertson was killed.

"I honestly feel lost without my mom, and it don't matter how old I am," she said while wearing a T-shirt and a button adorned with Chad's face. "She was literally the definition of strong; she would set her own struggles aside to help the next."

Taylor is haunted by the sight of her mother beneath a tangle of breathing tubes. It reminded her of coming to Robertson's bedside at a Chicago hospital to see him in the days after he was shot. The doctors' initial prognosis had been optimistic then, too, and Hackett, like her son, showed signs of improvement before she died.

For now, the grief is handled day by day. Several of her siblings moved into the tidy, two-bedroom apartment Nina Robertson shares with her boyfriend. Photos of Chad at various ages hang from every wall.

The couple, who have three children between them and were already planning to buy a new house, are now looking for something bigger, but money is tight. They paid for the funeral with money Hackett had set aside for emergencies.

Robertson described feeling a familiar sense of Hackett's absence as she tries to raise her younger siblings. Still, in many ways, she says, reality hasn't set in.

A week before her mother's death, she attended a court hearing for Tankson, the officer who shot Chad Robertson. Emotionally spent, she wept in the front row the whole time, then went outside to call her mom for solace.

Now both are gone.

She reflected on that day, then paused before continuing: "I'm an adult and I'm broken."

libor.jany@startribune.com 612-673-4064 •Twitter:@StribJany