Philadelphia police have enlisted the FBI to help investigate whether the fatal shooting of a convicted drug dealer last July is related to an earlier incident in which the victim claimed that he was shot by former Indianapolis Colts wide receiver Marvin Harrison, ESPN has learned.

The victim, Dwight Dixon, was killed in the Fairmount section of Philadelphia on July 21, 2009, when a gunman approached the driver's side of his Toyota Camry and fired four times, shot through the back window, and then fired two more times into the passenger side. Video surveillance taken by a camera at a nearby store shows the gunman -- wearing a hooded sweatshirt, jeans and white sneakers -- fleeing with his head lowered and face obscured. Dixon was struck in the chest, stomach and arm.

The location is a few blocks from a car wash owned by Harrison and down the street from his bar called Playmakers.

Moments after the shooting, Dixon told police who rushed to the scene that he believed the incident was related to an April 2008 assault in the same neighborhood, in which his truck was sprayed with gunfire and he suffered a bullet hole in his left hand.

Dixon, 33, lapsed into a coma before he could be interviewed by police. He died on Sept. 4 from the wounds. The Philadelphia Police Department still considers the case open and active.

Harrison, a 13-year NFL veteran, was released at his own request by the Colts at the end of the 2008 season after being asked to take a pay cut. He did not play in 2009.

In an exclusive interview with ESPN's "E:60" before the July 21 shooting, Dixon went into extensive detail about a shooting on April 29, 2008. He said that Harrison shot at him after the two had gotten into an altercation outside of the West Thompson Street car wash called Chuckie's.

"He raises the guns up and started shooting," Dixon said in the interview. "He raised both his hands up and started shooting at [my] truck."

When asked how many shots were fired, Dixon said, "Too many to count." He said his truck was so riddled by bullets, "the tires were all shot out, the windows were shot out."

Harrison has denied Dixon's claims, which are also part of a pending civil suit. Although police ballistics tests show that a gun registered to Harrison was used in the incident -- a Belgian-made semiautomatic pistol -- he insisted that he did not have it with him that day.

Through his attorney, Jerome Brown, Harrison declined to comment.

As ESPN The Magazine reported last January, a second witness, Robert Nixon, also told police that he saw Harrison fire a gun. Nixon, who was wounded in the back by stray gunfire, filed a civil suit against Harrison last July, claiming that the ex-wide receiver "continued shooting at the other person ... as [he] drove past plaintiff. In doing so, a bullet from defendant's handgun struck plaintiff in the back with great force and violence."

After an investigation, the Philadelphia district attorney's office announced that it was not bringing charges in connection with that incident.

"I'm pretty comfortable I know who fired the gun," District Attorney Lynn Abraham, who has since left the job, said at the time. But she added that she was could not go forward with just the statements of Nixon and Dixon. "With these witnesses, I don't think so," she said.

Dixon's death, however, has put the 2008 case back on the front burner. In September, Philadelphia voters went to the polls and elected a new district attorney, ex-prosecutor Seth Williams. And now, a task force of elite Philadelphia homicide investigators and the FBI is taking a fresh look at the shooting.

"We're looking for a motive of who would want to kill Dixon, so it's common sense to go back to that first shooting," a law enforcement source said. The source said that the FBI is helping to comb through old evidence and seek out new informants, one of whom has already been said to have supplied fresh information.

Shaun Assael is a senior writer for ESPN The Magazine.