Paranoid his girlfriend was betraying him to a rival gang, Anthony Nunnally allegedly shot and killed her in an East Side alley last October, prosecutors said in court Wednesday.
Just over a year before that, he allegedly killed another girlfriend in a different East Side alley in September 2024, shooting her several times.
The 21-year-old was charged this week with two counts of first-degree murder for their deaths. On Wednesday afternoon, Cook County Circuit Court Judge Deidre Dyer ordered him detained until trial.
Nunnally was already in Cook County jail for an unrelated carjacking charge. He allegedly tried to steal the car of a friend from grade school last October, around the time of the second killing, Cook County prosecutors said in court Wednesday.
At one point during his incarceration, his cellmate was a former member of the Latin Kings, the Chicago street gang to which Nunnally also allegedly belongs. The cellmate, wearing a wire, got Nunnally talking about the October 2025 murder, Cook County Assistant State’s Attorney Mike Pekara said in court.
Unaware he was being recorded, Nunnally told his cellmate that he was paranoid his 17-year-old girlfriend, Gabriella Arellano, was going to “backdoor him,” slang for betraying him to a rival gang.
When the cellmate asked if he felt any remorse for killing her, Nunnally allegedly said: “When some b – – – – backdoor you, you gotta do what you gotta do,” according to Pekara.
Arellano was found shot once in the head in an alley in the 11000 block of South Mackinaw Avenue on Oct. 26, 2025. Prosecutors said Wednesday that a nearby Ring camera captured the sound of the gunshot and then Nunnally and an unknown person running from the area. Another surveillance camera showed Nunnally, Arellano and the unknown person in the area before the girl was killed.
2024 murder
About a year earlier, on Sept. 28, 2024, 19-year-old Sierra Evans was found shot several times in the 9500 block of South Avenue N. Evans and Nunnally had been dating for about a month at the time she was killed, Pekara said.
The night she died, Evans, Nunnally and two other people were drinking and hanging out in a basement, Pekara said. At one point in the night, Nunnally allegedly got angry with Evans and choked and pinned her against a wall. He also punched a hole in the wall of the basement, at which point he was kicked out of the house, Pekara said.
Later, he called the two people and said he was in an Uber on his way back to the house, Pekara said. Minutes later, they heard several gunshots. Nunnally came running into the basement, holding a gun. He said he just killed someone and then flashed a gang sign. He did not say he killed Evans, Pekara said.
Evans was found the next day in a nearby alley with 18 shell casings next to her body.
About seven months later, Nunnally was allegedly threatening to hurt a new girlfriend. He pulled up a TV news clip of a memorial service for a Evans and told the new girlfriend he was going to do the same thing to her that he did to Evans, according to Pekara.
Scott Kozicki, the Cook County public defender representing Nunnally, said in court that prosecutors didn’t have enough evidence proving Nunnally shot both girls.
In the 2024 slaying, Kozicki said there was no evidence that the gun Nunnally came into the basement with matched the shell casings found at the crime scene. He also questioned the ability of the Ring camera to pick up the sound of a gunshot from the 2025 murder.
As for the confession to the Chicago street gang member, Kozicki said it was “really shaky, problematic entrapment.” He added that Nunnally’s cellmate had a great motive to sell him out.
“These are a lot of scary stories, but being near gunshots does not mean you participated in a shooting,” Kozicki said.
Pekara pushed back against that claim.
Nunnally “was the person last seen with each of these young women before they died. He was seen with a gun seconds after the first murder. In the second murder, the Ring camera got the sound of a gunshot and saw [Nunnally] running away,” Pekara said.
“He is a stone-cold killer,” Pekara added. “This is not a scary story, it’s a fact.”