Police Saturday began studying a video that shows Derrion Albert's death by beating.
The 2:26 video, which is very shaky, was apparently taken by two passerby who were driving a vehicle on the street where the melee occurred.
The video begins as the vehicle pulls up to the melee. Several youths are running back and forth in the street, and car horns and the screams of girls can be heard in the background.
At least two of the fighters wield long, weathered wooden boards.
The person videotaping the scene, apparently a man, can be heard making astonished comments as people are struck with the boards.
At about :50 through the video, Derrion is struck over the head by a board. He collapses to the ground, covering his head with his arms.
"Damn!" says the man behind the videocamera.
The videotape swings across the street to where the fight continues, then returns to Derrion, who seems to be dazed, but is sitting up and holding his arm above him.
That's when the gang members return, see him helpless, and begin to kick, stomp, and punch him on the ground.
"Oh my god they killing him look!" says the woman who accompanies the amateur videographer.
It is at this point that Derrion's friends and nearby workers come to Derrion's aid, picking him up and dragging him into a nearby building.
The video follows the group to the doorway of the building, then swings back to the fight.
"They beat him to death!" a man's voice says.
The videographer urges his companion to leave the scene of Derrion's death, and they walk down the block, where the fight continues.
"Damn," he says, then chuckles. "They still going at it down the street."
So far, police have not made any arrests. Anyone with information about Darrion's murder is urged to call 312-747-8272.