The Department of Public Safety, which oversees the Texas Rangers, did not immediately reply to a Saturday phone message seeking comment.
"It's not clear what (the) interaction was between her and the victim", Hall said.
The man, later identified as Uvaldo Perez, 46, took Guyger's Taser. "At some point she fired her weapon striking the victim", CNN wrote, quoting the chief.
Guyger was not charged in the 2017 shooting.
Police referred questions to the Rangers.
Amber Guyger, 30, who has been with the department for nearly five years, was not indicted in the 2017 shooting of the suspect who had taken her Taser from her during a struggle.
Authorities have said the officer is white, but haven't released her name or other details about her. Jean's mother is quoted by USA Today, asking that the officer "come clean.speak the truth", and she "will forgive her".
Guyger's arrest was announced as Jean's family and their attorneys say they met with prosecutors to demand the officer's arrest.
Flanked by area ministers and church leaders at a news conference after the prayer vigil, Lee Merritt, an attorney retained by Botham Jean's family, criticized the delay in taking the officer into custody.More news: Trump says he will delay border fight until after midterms
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On Saturday, the Texas Rangers, which is now handling the investigation, chose to postpone pursuing a warrant against Guyger "until they could follow up on information that they received from the interview with the officer", the Dallas Police Department said.
The incident began just before 10 p.m. CT (11 p.m. ET) at the South Side Flats, an upscale apartment complex directly south of Dallas' downtown. Jean's mother, Allison Jean, asked, according to the Associated Press. Afterward, she called 911, police said.
FacebookA woman posted videos on Instagram that she says show the aftermath of the Botham Jean police shooting.
"Preliminary information suggests that the officer arrived home in full uniform after working a full shift". The Rangers, she said, had interviewed Guyger and wanted to further investigate information obtained from her.
Chief U. Renee Hall said Saturday during a panel discussion livestreamed on Facebook by television station WFAA that the state investigators said they needed more time to investigate the Thursday night fatal shooting of 26-year-old Botham Jean. Jean didn't know the Dallas cop, reports say.
At a news conference early Friday, Dallas police Sgt. Warren Mitchell said they had yet to interview the officer and would not speculate as to whether she mistakenly entered another apartment and believed the man already inside was an intruder.
Hall issued condolences in a statement.
She reported the shooting to dispatchers and she told officers who responded that she had mistaken Mr Jean's apartment for her own.
Jean, 26, a native of St. Lucia who worked for PricewaterhouseCoopers in Dallas, died at a hospital. "Clearly, we need to let Chief Hall know that while we wish her well, we must hold her accountable also".
Hall said police aren't handling the case under the department's usual officer-involved shooting protocol.