Vick is not named in the documents.
The documents, filed Monday in U.S. District Court in Richmond and obtained Friday by The Associated Press, contain the address of the home that has been the center of the investigation.
According to the documents, dog fights have been sponsored by "Bad Newz Kennels" at the property since at least 2002. For the events, participants and dogs traveled from South Carolina, North Carolina, Maryland, New York, Texas and other states. Members of the venture also knowingly transported, delivered and received dogs for animal fighting, the documents state.
Fifty-four animals were recovered from the property during searches in April, along with a "rape stand," used to hold dogs in place for mating; an electric treadmill modified for dogs; and a bloodied piece of carpeting, the documents said.
The property was used as the "main staging area for housing and training the pit bulls involved in the dog fighting venture," according to the filings.
The documents said the fights usually occurred late at night or in the early morning and would last several hours. The winning dog would win from "100's up to 1,000's of dollars," and participants and spectators also would place bets on the fight.
Fights would end when one dog died or with the surrender of the losing dog, which was sometimes put to death by drowning, strangulation, hanging, gunshot, electrocution or some other method, according to the documents.
During a June search of the property, investigators uncovered the graves of seven pit bulls that were killed by members of "Bad Newz Kennels" following sessions to test whether dogs would be good fighters, the documents said.
Members of "Bad Newz Kennels" also sponsored and exhibited fights in other parts of Virginia, North Carolina, South Carolina, Maryland, New Jersey and other states, the filings said.
Federal agents used shovels and heavy equipment earlier Friday to search the property.
A backhoe-front loader was brought in and used to scoop up sections of a cleared wooded area in the rear of the property. The material was dumped into ice-filled coolers and loaded into a rental truck, which left the property.
Some of the investigators wore T-shirts reading: "Federal Agent USDA."
An Associated Press reporter and photographer viewing the investigation in a helicopter could not clearly identify the evidence being collected.
Investigators were digging in an area about 50 yards behind the large white house on the property. Earlier, officials worked under a blue tarp to sift earth collected in white buckets. Some wore T-shirts with the wording "POLICE."
About 15 people could be seen on the property, which included kennels and outbuildings.
Sources said the agents are looking for additional dog remains on the property, reports WAVY-TV.
One of the investigators told the news media assembled outside the property the search would take a considerable amount of time.
The expansive property in southeast Virginia has a metal gate at the entrance and a fence around the perimeter, which obscured the work of investigators. Fifteen vehicles were on the property, including the rental truck and a Virginia State Police evidence collection truck.
Corinne Geller, a spokesman for the Virginia State Police, said state authorities were working with federal investigators in an "assistance capacity."
During an April 25 drug raid at the property, authorities seized 66 dogs, including 55 pit bulls, and equipment commonly used in dogfighting. About half the dogs were tethered to car axles with heavy chains that allowed the dogs to get close to each other, but not to have contact, an arrangement typical for fighting dogs, according to the search warrant affidavit.
Later, after an informant suggested authorities could find as many as 30 dogs buried on the property, including seven buried only days before the initial raid. Surry County officials secured a search warrant, but never acted on it because prosecutor Gerald G. Poindexter said he had concerns with the document.
On June 7, the day that warrant expired, federal officials executed their own with the help of state police investigators.
Poindexter publicly questioned the federal government's interest in a dogfighting case. He suggested that Vick's celebrity was the draw, and raised race as a possible motivation as well. Poindexter and Vick are black, as is Sheriff Harold Brown.
Vick has said he had no idea the property may have been used in a criminal enterprise and blamed family members for taking advantage of his generosity. He also put the house up for sale and reportedly sold it quickly.