The FBI hasn't said why the Safe Streets Task Force raided the sites. The group is comprised of federal, state and local officers and focuses on gangs and illegal drugs and firearms.
Fabini said Thursday in a statement issued by his attorney, Patrick Murphy, that he's not the investigation's target and has done nothing wrong. There is no phone listing for his brother, Michael Fabini.
"I have cooperated fully with authorities, and will continue to do so. I have not been charged, nor do I expect to be charged with a crime," the former player said. "I expect the community will have many questions as rumors circulate and this investigation continues, but I ask that we trust in the authorities to do their job."
Murphy didn't respond to a phone message seeking comment Friday.
FBI Special Agent David Crawford declined to say whether Friday's raids were connected to Thursday's. He would only confirm that there was "investigative activity" at those addresses. Local authorities didn't respond to phone requests for comment.
There was no record of any charges or indictments involving either of the Fabinis on the online federal court docket Friday.
Fabini played 11 NFL seasons, including eight with the Jets, one with the Dallas Cowboys and two with the Washington Redskins. His last season was in 2008.
Local news outlets reported that officers were seen carrying items out of Michael Fabini's house in an upscale subdivision and loading them into trucks. At least one police dog also took part in the search, although authorities declined to say what it was trained to find. Several police vehicles and FBI agents remained at the home through most of Thursday as neighbors and television news trucks stood watch nearby.
Security cameras are clearly visible at the corners of the house.
WANE-TV reported that officers carried armloads of guns out of one of the homes raided Friday.
Online property records say that Michael Fabini's four-bedroom home measures some 6,000 square feet, including nearly 3,200 in the basement and a 1,200-square-foot garage. He bought the home in 2009 for $270,000, records say.