The Dallas jury could have handed down a sentence between five and 99 years to Amber Guyger, 31, for killing 26-year-old Botham Jean, who worked for an accounting firm.
Guyger, who is white, had claimed she thought Jean, who was black, was an intruder in her own apartment.
In fact, she had entered Jean’s unlocked apartment, located in the same building but one floor above hers.
“The jury has convicted Amber Guyger of ten years. Of course that’s inadequate,” the lawyer for Jean’s family Lee Merritt said on Twitter. “The entire justice system is inadequate and the work must continue.”
The shooting and its aftermath sparked demonstrations and appeals for justice in a nation where white police officers who shoot people of colour often go free.
On the night of the shooting, Guyger was still wearing her police uniform after a nearly 14-hour shift.
Jean, who was unarmed, was sitting on the couch in his apartment, number 1478. Guyger lived in 1378.
Guyger’s lawyer had told the court his client had made a “tragic mistake,” but that she was not “evil.”
“I ask God for forgiveness, and I hate myself every single day,” Guyger said during the trial, which begin in September.
“I never wanted to take an innocent person’s life.”
But prosecutors said she had missed several opportunities to realise that she was on the wrong floor and should have called for back-up.
They had asked for a sentence of 28 years.
Jurors were given the option of finding Guyger guilty of the lesser offense of manslaughter, but a grand jury indicted her on the more serious charge of murder following the protests. (AFP)