Cops bailed celebrity fixer Chris Nathaniel, 39, after quizzing him over the death of 18-year-old Danny O'Shea, who was stabbed in the neck outside his mother's east London home in December last year.
Nathaniel, head of the NVA Entertainment Group, last year brokered a multimillion dollar deal between Jay-Z and Chelsea star Cole to open a London branch of the US rapper's 40/40 restaurant and bar franchise.
At the time of the deal, he said, "We have done some exciting deals and worked with some world-class names, but this collaboration of Ashley Cole and Jay-Z has to be one of the most exciting, and it makes the nine months of negotiations worth it."
Nathaniel was seized by murder squad cops when he landed at London's Heathrow Airport on Monday after a flight from the US.
He was held with an unnamed friend aged 33, and both were questioned about the murder. The pair was later freed on bail until March, pending further inquiries.
The entertainment guru -- linked with a host of sports idols, showbiz stars and leading lawmakers -- was the middleman in a seven-figure book deal for Cole's teammate, England star John Terry -- and claims to promote the world's fastest athlete, Usain Bolt.
Nathaniel was also a director of soccer ace and anti-knife-crime campaigner Rio Ferdinand's Live The Dream Foundation for disadvantaged youngsters until he quit five days before his arrest. He sat in on meetings between Ferdinand and former British prime ministers Tony Blair and Gordon Brown.
Nine other suspects aged from 22 to 43 have been held and bailed in connection with O'Shea's murder, and on Tuesday, police repeated their appeal for witnesses to come forward.