Arshell Dennis, 19-year old journalism student, was gunned down on the steps of his mother's home in what police are saying was an arbitrary killing. Dennis reportedly was there to surprise his sick mother on her birthday. (Reuters)

Arshell “Trey” Dennis, the third of his name, moved to New York to escape the home he loved.

He grew up in the South Side of Chicago, a city that employs his father as a police officer but has also profiled the 19-year-old because of the color of his skin. It’s a city seemingly constantly in turmoil — bleeding each weekend from dozens of gun-related killings — and an environment Dennis said he felt thankful to leave.

“I do appreciate that I am where I am,” he told his college roommate in a video interview last year. “A lot of people where I’m from don’t make it out.”

The teen had plans: to graduate from St. John’s University in New York City and become a writer, to channel what he’d learned about poetry and struggle into words that might make something shift. He couldn’t change the world — he said for that he’d need two lifetimes — but Dennis felt his path, where he came from and what he knew, might be able to “influence.”

“If you don’t know me,” he said in the video, “you gonna know me.”

Just weeks from entering his junior year at St. John’s, the aspiring journalist and past NAACP student chapter vice president flew back home to Chicago for the weekend, WGN TV reported, a surprise for his sick mother’s birthday.

He sat on the porch of his family’s home Saturday night, talking with a hometown friend, when gunfire split the stillness of his ordinarily quiet Wrightwood neighborhood.

Both were shot.

The friend, 20 years old, was hospitalized.

Dennis died.

His mother’s screams echoed down the block.

“You do not want to hear a mother’s cry for her son,” a neighbor, who would only identify herself as Brenda, told the Chicago Tribune.

As of late Monday night, there had been no arrest, and authorities said the investigation was still open and active.

In a news conference Monday afternoon, Chicago Police Department Superintendent Eddie Johnson said authorities were treating the shooting as a case of “mistaken identity.”

“Arshell was a good kid, making his parents proud and studying for a promising future,” Johnson said in a statement.

The superintendent, who worked with Dennis’s father, Officer Arshell “Chico” Dennis, in the 1990s, visited the family Sunday and said in the statement he was “at a loss for words for the amount of grief” they are experiencing.

Though it’s well known in the neighborhood that the elder Dennis, a Drug Enforcement Administration task force officer, worked for the Chicago Police Department, the superintendent said there is “absolutely no credibility” to the theory that Arshell was targeted because of his father’s occupation.

The two young men had no criminal records or personal histories of gang involvement, a police spokesman told the Chicago Tribune, but the shooting could still be gang-related. Some gangs have been conducting initiations, a police official told the Chicago Sun-Times, where recruits are instructed to shoot and kill whomever they find.

“That’s a rite of passage for them,” Johnson told CBS News. “Now how bizarre is that?”

On Sunday, the day Dennis was to return to New York, his loved ones scrubbed his blood from their sidewalk instead.

“The loss of our son is stunning and painful,” the Dennis family said in a statement to the Sun-Times. “Tragically, we were going to take him to the airport today at 3 p.m. to return to school. Now because of this senseless violence, we will be grieving and planning his funeral. Trey was smart, funny, and the light of our lives.”

Dennis graduated from Urban Prep Academy in 2014, where he ran cross country, played chess and participated in the Louder Than a Bomb poetry competition, according to his LinkedIn page. He also belonged to a preparatory program called Upward Bound. It was from a student in the program that director Gerald Smith heard the tragic news.

“I got the phone call, and my heart just fell to my stomach,” Smith told the Tribune. “So, so unexpected. … I’m still in disbelief.”

Last summer, Dennis returned to Chicago to work as an Upward Bound ambassador, Smith said.

“He was one of my better students, he really was,” Smith said. “Arshell was a fun time. He was real easygoing, real quiet, laid-back, mild-mannered — he wasn’t a problem at all. It’s a tragic loss.”

Terri Bachstrom, a neighbor and lunchroom attendant in Chicago Public Schools, told the Sun-Times Dennis was a well-mannered, quiet kid.

“He wasn’t in a gang. He wasn’t affiliated with any of the nonsense that’s going on in Chicago,” Bachstrom said. “He wasn’t one of those kids.”

Johnson said at the news conference Monday that to date in 2016, 85 percent of gunshot victims have had prior contact with police. Dennis and his friend were the exception, and yet this weekend, the two became part of the city’s growing violence statistics. In the same weekend Dennis died, nine people were killed and 31 more wounded in shootings across Chicago.

Since Jan. 1, 2,607 people have been shot in the city, according to a Chicago Tribune analysis, on pace to far exceed the number of shootings last year, which totaled 2,988.

It’s the kind of violence that Dennis used to discuss at St. John’s with his freshman-year roommate, 20-year-old Kyle DePina of Boston, reported the Sun-Times.

“It’s crazy,” DePina told the newspaper. “You never think it will happen to someone you’re close to until it happens.”

It was DePina who recorded Dennis in the 8-minute interview posted to YouTube in April 2015. They talk about police brutality and racial stereotypes. DePina asks his friend about his goals, what he wants to do, who he wants to be.

“I do think that I’ll be able to influence a lot the way people think,” Dennis said. “And give them an outlook on the things I’ve been through, and things that people where I come from go through, and just help them get through the struggles that they go through.”

That potential was universally mourned over the weekend.

“He was a promising child,” Brenda, the neighbor, told the Sun-Times. “He was going somewhere.”