Vick, however, insisted he placed no bets of his own nor took any winnings.
Sportswear giant Nike severed its ties with the Atlanta Falcons quarterback yesterday, issuing a statement that said "Nike has terminated our contract with Michael Vick following yesterday's release of details of his plea. As we have said in previous statements, we consider any cruelty to animals inhumane, abhorrent and unacceptable."
Nike suspended Vick's contract last month and said items bearing his name would no longer appear in company-owned stores. Nike also has decided not to release a fifth signature shoe, the Air Zoom Vick V, this summer.
Terms of his deal with Nike have not been released.
In disciplining Vick, commissioner Roger Goodell said Vick's admitted conduct was "not only illegal but also cruel and reprehensible" and regardless whether he personally placed bets, "your actions in funding the betting and your association with illegal gambling both violate the terms of your NFL player contract and expose you to corrupting influences in derogation of one of the most fundamental responsibilities of an NFL player."
A "summary of facts" signed by Vick was filed along with his written plea agreement on a federal dogfighting conspiracy charge. He will appear before U.S. District Judge Henry E. Hudson to formally plead guilty Monday and then await sentencing at a later date.
The court documents and a statement by Vick's legal team seek to portray him as less involved in the dogfighting ring than three co-defendants who previously pleaded guilty and agreed to testify against the Atlanta Falcons quarterback.
"While Mr. Vick is not personally charged with or responsible for committing all of the acts alleged in the indictment, as with any conspiracy charge, he is taking full responsibility for his actions and the actions of the others involved," the defense team said in a written statement after the plea agreement was filed.
"Mr. Vick apologizes for his poor judgment in associating himself with those involved in dog fighting and realizes he should never have been involved in this conduct," the statement said.
Vick signed the plea agreement late Thursday.
"Most of the Bad Newz Kennels operation and gambling monies were provided by Vick," a summary of facts in the case said, echoing language in plea agreements by three co-defendants who previously pleaded guilty.
The statement said that when the kennel's dogs won, the gambling proceeds were generally shared by Vick's three co-defendants — Tony Taylor, Purnell Peace and Quanis Phillips.
"Vick did not gamble by placing side bets on any of the fights. Vick did not receive any of the proceeds of the purses that were won by Bad Newz Kennels," the summary said.
According to the statement, Vick also was involved with the others in killing six to eight dogs that did not perform well in testing sessions last April. The dogs were executed by drowning or hanging.
Dan Dierdorf, NFL Analyst for CBS Sports, said, "I don't know there's a whole lot of difference between being the guy that actually drowned, hung or electrocuted a dog, or knowing that it was being done on your property to your dogs by your friends."
In the plea agreement, the government committed to recommending a sentence on the low end of the federal sentencing guideline range of a year to 18 months. However, the conspiracy charge is punishable by up to five years in prison, and the judge is not bound by any recommendation or by the sentencing guidelines.
Hudson has a reputation for imposing stiff sentences, according to lawyers who have appeared in his court. The judge will set a sentencing date at Monday's hearing.
"Our position has been that we are going to try to help Judge Hudson understand all the facts and Michael's role," Vick's defense attorney, Billy Martin, said in telephone interview. "Michael's role was different than others associated with this incident."
Martin said Vick will "speak to the public and explain his actions." Though he declined to say when and where, the "Tom Joyner Morning Show," a syndicated program based in Dallas, said it will have a live interview with Vick on Tuesday.
It is not uncommon in plea agreements for the defendant to plead guilty to only one charge and to negotiate with prosecutors over the specific facts to which he'll be admitting, CBS News legal analyst Andrew Cohen said. In this case, prosecutors may not care that he's not admitting to gambling so long as he gets a significant prison sentence.
The U.S. Attorney's office, which has declined to comment on the case, said it would issue a statement after the hearing.