Detectives are poring over video from local surveillance cameras and have found a bloody 7-inch switchblade in a nearby Dumpster, but they have not determined what prompted the attack, police said.

The killing may have stemmed from a fight between two women in the club, although it was not clear how Shamel McKinney became involved, police said. Because of the fight, cops had been called to the nightspot - which features 30 beds framed by silk curtains for what the Duvet Web site calls a "sexy" experience. Police were outside when McKinney collapsed.

"The fight broke out, but he had nothing to do with it," said the victim’s brother Darryl McKinney, 23, who was at the club. "He got caught in the middle. He wasn’t with the girls. He was just standing there."

"He was a good father," said his brother, who at the thought of his sibling’s two small children became too distraught to say more.

Shamel McKinney was a longtime friend of Fabolous. They knew each other since their childhood in Bedford-Stuyvesant, Brooklyn. Shamel McKinney was apparently identified wearing the Street Family Crew chain.

Police sources said Fabolous was at the W. 21st St. club in the hours before McKinney was killed, though the dead man’s family insisted Friday that the rapper was not there.

McKinney’s devastated relatives and friends gathered at his family’s Crown Heights, Brooklyn, apartment to mourn the popular young father of two and pick a casket for his funeral.