Philadelphia Eagles quarterback Michael Vick has called a timeout.

Vick has canceled book signing appearances in several states, including one in Chester County, because of violent threats.

The NFL star faced years of criticism for his troubled past. He has spent the off season promoting the power of a second chance in his autobiography titled, "Finally Free."

Book tour appearances have been halted after his spokesman, Chris Shigus, confirmed Vick received what they called, "credible threats."

"We had an uptick in the level of threats that were made against Michael Vick as well as his family," said Shigus.

"I think you should leave his family alone. He did what he did and paid his dues," said Michael Ewing, a Dallas Cowboys fan from Malvern, Pa.

According to Vick's spokesman, he's canceled appearances in Atlanta, New Jersey and at the Barnes & Noble in Exton, Chester Co.  

Threats were reportedly made against the bookstore and its employees, as well.

"Employees and the store seems pretty far removed from the situation," said Will Harbison, from Coatesville, Pa.

Vick is no stranger to negative publicity. He served 18 months in federal prison after pleading guilty to dogfighting charges in 2007. Criticism and protests followed after he signed with the Philadelphia Eagles.  

The Humane Society of Berks County admitted Vick made poor choices in the past but said the threats are unacceptable.

"It's never appropriate to threaten violence against someone else, and to bring his children into it is another level," said Dylan Heckart, Humane Society of Berks County.

The Eagles organization donated $50,000 to the Humane Society in Berks to further animal welfare.

The threats subsided over the years, but recently they exploded, Shigus said.

"We're confident the authorities are taking these threats very seriously, and they'll be investigated fully," said Shigus.

In the meantime, Vick's appearances have been sidelined.