* Officer had taser on him at time of shooting
* Man ran at officer, did not stop when ordered to
* Police chief: Man may have had mental illness
March 9 (Reuters) - A white, Atlanta-area police officer shot dead a naked and unarmed African-American man acting erratically in his apartment complex and who was possibly suffering from a mental illness, the county police chief said.
A Dekalb County police officer responded to a caller who said a man was "acting deranged, knocking on doors, and crawling around on the ground naked," on Monday around 1 p.m. local time, county police chief Cedric Alexander told reporters.
The officer encountered the man, who was not wearing any clothes, in the parking lot, Alexander said at a conference published online by local broadcaster Fox5.
Alexander said the man ran at the officer, who backed up and ordered the person to stop before shooting him twice. Police did not find a weapon at the scene, he said.
Monday's shooting comes after a string of killings of unarmed black men by police in the United States. Last year, incidents in Ferguson, Missouri and New York City prompted nationwide protests, some of which turned violent.
This is at least the third African-American man to be shot dead by police since last Friday, who either was or seemed unarmed.
Dekalb County police has already faced protests after an officer shot dead a black man who had called 911 when his girlfriend was stabbed by an attacker in his apartment late last year, according to local media.
Alexander said he could "reasonably assume" the person was possibly suffering from mental illness, given his behavior. He declined to identify the victim, but the New York Times reported that he was 27-year-old Anthony Hill.
Alexander said the officer, who had been with the department for seven years, was equipped with a taser at the time of the shooting. The Georgia Bureau of Investigation would handle Monday's incident, he said.
Police near Denver last Friday shot dead an unarmed man who was a wanted fugitive. On the same day, an officer in Madison, Wisconsin, shot dead a 19-year-old, prompting some 2,000 students to march in the state's capital on Monday. (Reporting by Curtis Skinner in San Francisco; Editing by Nick Macfie and Raissa Kasolowsky)