She had worked at a clothing distribution center for ThredUp, an online consignment store, and had a job interview scheduled for this week.
Her family said she always wanted to lend a helping hand and often offered them pep talks when they were down. The teenager also loved to look pretty.
"She wouldn't go anywhere without looking presentable," Wilson's sister, Malika Harris, told the New York Times. "She was really passionate about the way she looked and carried herself."
What happened during the attack?
Wilson was fatally stabbed, and her 26-year-old sister, Lahtifa Wilson, was seriously injured during an attack on the BART MacArthur station, according to The Associated Press.
Surveillance video on the train and at the station's platform showed John Lee Cowell, 27, had been riding the same car as the sisters, but they did not interact, BART police Chief Carlos Rojas said at a news conference Monday.
As the group got on the platform, Cowell attacked with a knife.
“It looks like it was an unprovoked, unwarranted, vicious attack,” Rojas said.
During an interview with a local news station, Lahtifa Wilson said Cowell did not speak.
“All of a sudden, we transfer just to get blindsided by a maniac, for what I don't know,” she said. “I looked back and he was wiping off his knife and stood at the stairs and just looked. From then on, I was caring for my sister.”
Has the attacker been arrested?
Cowell was arrested peacefully Monday night aboard a train about a dozen miles away from where the incident took place, according to the AP. An anonymous tip from a rider on a BART train led to the arrest, authorities said.
On Wednesday, he was arraigned on a charge of murder with a deadly weapon in the slaying of Nia Wilson. He was also charged with attempted murder in Lahtifa Wilson’s stabbing.
Cowell, a paroled convict, has a long list of previous criminal charges, as well as a history of mental illness, according to the reports. He was released from state prison in May, just 75 days after completing a sentence for second-degree robbery. He also had prior arrests that include assault with a deadly weapon, the East Bay Times reported.
Was the attack racially motivated?
There has been speculation that the crime could be racially motivated, since Cowell is white and the Wilson sisters were black. Investigators said they have found no evidence of racial motivation, but Oakland Mayor Libby Schaaf said in a statement on Facebook, “Oakland has no room for hate or white supremacy.”
During the press conference Monday, Rojas said, “Up to this point, we do not have any information that suggests it is race-motivated, but we cannot discount it at this time. We don’t have a motive.”
“We don’t know if it was racist, we don’t know if it was random, we don’t know what it was,” Daryle Allums, Nia Wilson’s godfather, added. “Let’s get this information to find out what really happened. Let’s find out the right facts, so then we’re able to deal with this situation.”
How has the community responded?
About 1,000 protesters in California took to the streets to remember Nia Wilson and demand justice Monday evening. The march began at the scene of the attack, where they also held a vigil, and moved to downtown Oakland.
"I feel that the community has failed people of color for one. I feel that BART has failed us from the beginning with Oscar Grant," Jinina Knox, a friend of Nia Wilson's family told a local news station. "How do we let a man get on BART, slit a woman's throat, stab her to death and walk off through our community and no stopping him?"
On Thursday, about 50 protesters marched to local news station KTVU after it aired a photo that appeared to show Nia Wilson holding a gun, according to the East Bay Express. Activists said it was a cellphone case, and they believe the image was used to perpetuate stereotypes of African-Americans.
The National Association of Black Journalists, the Bay Area Black Journalists Association and the Robert C. Maynard Institute for Journalism Education later released a joint statement to condemn the news station.
"The use of the photo can be seen as an attempt to dismiss her [Wilson's] humanity and silence those who view her death as a racially-motivated attack," the organizations wrote. "Such depictions reinforce unconscious bias, particularly against people of color, who are over-represented in stories about crime and violence."
Have celebrities responded?
Yes, several celebrities, including Kehlani, Viola Davis, Anne Hathaway and Janelle Monae have taken to social media to express their thoughts.
The Associated Press contributed to this report.