A jury believed Lafayette Cosby acted in self-defense the first time he was charged with killing a man, but not the second time.
Jurors deliberated less than four hours Friday before finding Cosby guilty of first-degree murder in the April 4 shooting of Robert T. Martin, an acquaintance, at a party at Jefferson Commons, 2511 W. 31st St.
The verdict meant jurors didn't believe Cosby's story that he shot Martin because Martin was concealing a gun under a jacket on his lap and was just turning to shoot another man.
A key piece of testimony was that the man Cosby claimed he was trying to protect -- who was sitting next to Martin on a couch -- didn't see Martin holding the jacket or a gun.
Assistant Dist. Atty. Dave Zabel told jurors during closing arguments that Cosby shot Martin because of a "fantasy" Cosby had that Martin was trying to kill him.
"He decided to be jury, judge and executioner," Zabel said. "There was no provocation. There was no justification."
Throughout the trial, Cosby's attorney, Greg Robinson, characterized the 28-year-old Martin -- known by the nickname "Man-Man" -- as a dangerous, unpredictable drug dealer who was capable of harming people without notice.
Martin's family members said the Robert Martin they knew was a gentleman who loved his five children.
"He was a good son and a good father," said his mother, Eula Martin, of Leavenworth.
She said it comforted her to know Cosby was no longer "sitting around smug, like he didn't do anything wrong."
Kim Foster, Martin's girlfriend, said Martin didn't have ill will for Cosby, and she didn't understand why Cosby shot him. Foster said Cosby's personality had changed after a 1997 incident in which he stabbed and killed one of Martin's friends, David E. Walker II.
A jury later acquitted Cosby of manslaughter, finding he acted in self-defense.
Cosby, 25, is to be sentenced Dec. 7. Premeditated murder typically carries a life sentence with parole eligibility after 25 years.
Dist. Atty. Christine Kenney said the verdict was bittersweet.
"It is always difficult in a murder prosecution, to see the devastation for all the families involved and to know that there are children out there that are going to be raised without a father," she said.