Ronald Jones was the next witness to testify after 28-year-old Joshua Brown, who was shot dead Friday in a Dallas parking lot.
Social media erupted following the shooting of Brown, with many expressing fear for the life of Jones and other witnesses and worrying that someone could be targeting them.
Jones was a neighbor of the murder victim, Botham Jean. He testified he saw Guyger's white truck speeding into the apartment building parking lot minutes before the murder.
Brown wept on the witness stand during his testimony against Guyger. It was crucial to the prosecution case because it directly contradicted Guyger's story.
Guyger had said she told Jean to put his hands up before she fatally shot him on Sept. 6, 2018, after coming home from work and walking into his apartment that she said she mistook for her own.
But Brown said he didn't recall hearing her say that.
Attorney Lee Merritt said Brown had feared for his life. He was also set to testify in a civil trial brought by Jean's family against the city of Dallas. And Brown had been a witness to the murder of another man in November.
“To have a key witness suddenly be killed is suspicious. Was this related to the trial? There is no clear indication,” he told CBS News.
Guyger was found guilty of murder in the death of Jean and sentenced to 10 years in prison.