(CNN) – Two weeks ago, almost no one had heard of Joshua Brown.
The 28-year-old was catapulted into the spotlight when he reluctantly testified at the trial for murder of the Dallas pillage of Amber Guyger, who was convicted of killing his neighbor, Botham Jean.
Ten days after he testified, Brown was shot dead and became a victim of the armed violence he had always feared.RELATED
This is what we know and do not know about the case.
What we know
Brown told the jury important details of the night Botham Jean was killed
Brown was visibly shaken after the murder of Botham Jean, who lived directly across the hall last year in the South Side Lofts apartment building in Dallas.
The two men met only a few hours before Guyger allegedly confused Jean's apartment with his own, entered and killed Jean, thinking he was an intruder.
On the night of September 6, 2018, Brown returned home almost at the same time that Guyger entered Jean's apartment.
Brown said he was at the end of the hall when he heard the voices of two people who sounded like they were "surprised."
Shooting occurred "just after," Brown said.
Later, Brown said, he saw Guyger leave Jean's apartment and walk down the hall. The agent was talking on the phone.
He was "crying, explaining what happened, what he thought happened, saying he entered the wrong apartment," Brown said.
Through his peephole, Brown said he saw the police "coming and going with the phone."
Brown testified that he didn't hear anyone say something like “Stop! Police!". But he said it was difficult to distinguish the brief and frantic words between Guyger and Jean.
The witness was killed in front of his new department
About three months after Jean's death, Brown moved from South Side Flats.
He tried to maintain an "intentionally low profile," said attorney S. Lee Merritt, who represents the Jean and Brown families.
Brown moved to the Atera Apartments in Dallas, about 8 miles from his former complex.
On Friday night, an assailant shot and killed Brown in the parking lot of the Atera Apartments.
Witnesses told police they saw a silver four-door sedan leaving the parking lot just after the shooting.
What we don't know
Who killed Brown and why
So far, the police have not made arrests for Brown's death.
Investigators also do not know what the reason was, said Dallas police chief, U. Renee Hall.
The authorities have not reported whether Brown's death has any connection to his testimony at the Guyger trial.
Is the murder related to the previous occasion when Brown was shot?
Brown had survived a shooting almost a year before his death, Merritt said.
He was shot near a strip club in Dallas in November 2018, Merritt said.
Brown and his family believed he was attacked in that shooting by someone he knew and had grown up with.
Another man, Nicholas Shaquan Diggs, died in the shooting, Merritt said.
After Brown was shot last year, "he was worried that that person could try to return and finish the job," Merritt said.
The author of that shooting has not yet been arrested.
Ashley Killough and Ed Lavandera of CNN contributed to this report.