Investigators said almost nothing to reporters who gathered at the property while agents conducted a second search on Friday, but documents filed in Richmond and obtained by The Associated Press detailed aspects of the case for the first time. Vick is not named in the documents.
The property was used as the "main staging area for housing and training the pit bulls involved" in a dogfighting operation, according to the court papers.
The documents contend prize money from the dogfighting climbed into the thousands of dollars, people came from as far away as Texas and sheepish pit bulls were killed.
As federal agents used a backhoe to dig in an area about 10 feet wide by 20 feet long behind the massive two-story home, then left at about 4:30 p.m., the documents shed some light on their investigation.
They allege that dogfights 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.
Fifty-four pit bulls 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 documents said the fights usually occurred late at night or in the early morning and would last several hours.
Before fights, the participating dogs of the same sex would be weighed and bathed, according to the filings. Opposing dogs would be washed to remove any poison or narcotic placed on the dog's coat that could affect the other dog's performance.
Sometimes, dogs weren't fed to "make it more hungry for the other dog."
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, gun shot, electrocution or some other method, according to the documents. The property has an aboveground swimming pool, and investigators were seen looking into its murky water Friday.
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 the dogs would be good fighters, the documents alleged.
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, according to the filings.
On Vick's Web site, he lists his birthplace as Newport News, "a.k.a. BadNews."
Friday, federal agents used shovels and heavy equipment to search the Vick property, where an informant told authorities as many as 30 dogs could be buried.
A backhoe-front loader was brought in and used to excavate a cleared area on the property. The material found to be of interest was transferred into numerous large, ice-filled coolers and loaded into a rental truck, which left the property.
An Associated Press reporter and photographer viewing the investigation from a helicopter could not clearly identify the evidence being collected.
Investigators were digging in an area about 50 yards behind a large white house. About 15 people could be seen on the property, which includes several kennels surrounded by pens made of metal fencing, other kennels and outbuildings.
Located in southeast Virginia, the expansive property has a metal gate at the entrance and a white plastic fence around the perimeter. The fence and a large two-story building painted black behind the home obscured the work of investigators.
More than 15 vehicles were on the property, including the rental truck and at least one Virginia State Police evidence collection truck.
Corinne Geller, a spokeswoman for the Virginia State Police, said state authorities were working with federal investigators in an "assistance capacity."
Vick has said he rarely visited the property. No charges have been filed.
During an April 25 raid at the property, about half the dogs were tethered to car axles with heavy chains that allowed them to get close to each other, but not to have contact, an arrangement typical for fighting dogs, according to an affidavit.
Later, Surry County officials secured a search warrant based on an informant's information about dogs being buried on the property, but never acted on it because prosecutor Gerald G. Poindexter said he had concerns with the wording of 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 Vick's celebrity was the draw and raised race as a possible motivation. Poindexter and Vick are black, as is Surry County Sheriff Harold Brown.
Poindexter, on vacation in Louisiana, said by telephone he was unaware of Friday's search and was still pursuing what he called a parallel investigation. He said he assumed Surry County and federal officials eventually will share their evidence.
Vick initially said he had no idea the property might 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, although there is no record that the sale has closed. Vick has since declined to talk about the investigation.
Michael Felberbaum reported from Richmond.