This followed the fatal shooting of Ademola Ade in the January 9, 2012, Lagos fuel subsidy protest.
Justice Akinlade also found Fabunmi, a dismissed chief superintendent of police (CSP), guilty of shooting and injuring three others; Alimi Abubakar, Egbujor Samuel and Chizorba Odoh.
She sentenced him to five years on this count, but both sentences are to run concurrently.
Fabunmi, of 12 Oyewole Street, Ogudu, Lagos, who joined the police in 1984, was arraigned on May 5, 2013, by Lagos State on a seven-count of murder, attempted murder and causing grievous bodily harm.
At the time of the incident, the defendant was the DPO of Pen Cinema Police Station, Agege.
He led his men to Yaya-Abatan in Ogba, following reports that there was a disturbance and hoodlums were holding people hostage.
The ex-DPO testified that when he got there, the hoodlums threw bottles, sticks, cutlasses, stones at him and his seven colleagues.
Fabunmi said during the attack by the mob, his rifle, containing 60 bullets, went off.But he denied shooting the deceased or anyone else.
The judge rejected defence argument that the shooting was the result of an accident as the defendant struggled with the mob to re-possession his rifle.
The deceased, a fashion designer, was shot in the thigh and was rejected at a hospital for want of a police report.
The other three had testified that by the time they were taken to Ikeja General Hospital it was too late.
The deceased bled to death before treatment could begin.