The former Dallas Police officer who shot and killed an unarmed black man in his own apartment after allegedly mistaking it for her own was charged with murder Friday, according to NBC News.

The ex-officer, 30-year-old Amber Guyger, was initially arrested in September on a manslaughter charge and released on bond after fatal shooting of 26-year-old Botham Jean.

"I truly believe that she inflicted tremendous evil on my son," said Allison Jean, Botham's mother, according to The Dallas Morning News. "I look forward to the next test, which is a proper conviction of murder of Amber Guyger, and more so of a penalty, a proper penalty so she can reflect on what she has done."

If Guyger is convicted, she will face up to life in prison. The manslaughter charge she was initially facing carried a maximum penalty of 20 years.

Dallas County District Attorney Faith Johnson said "we presented the evidence and we explained the law" to the grand jury, explaining why the charge was elevated to murder.

"At the moment of the shooting it was a knowing ... offense," Johnson said, according to CNN.

What allegedly happened: Guyger said that she drove to her apartment complex after work one night, but unintentionally got off on the wrong floor and went to the apartment occupied by Jean.

When she got to the apartment, she encountered Jean and said she thought he was a burglar, so she shot and killed him after he didn't follow her commands.

About Botham Jean: Jean was originally from St. Lucia in the Caribbean, and had moved to Dallas to work at Pricewaterhouse Cooper, according to his mother.

"I'm really grateful for the life that he lived," Allison Jean said. "I feel it's unfair in the way that he died at such a young age. But, on the other hand, I'm thankful for the impact he made on people's lives.