Michael Vick has canceled appearances to promote his new book. (Matt Rourke / AP)

Michael Vick has canceled appearances to promote his new book because of death threats against him and his family.

Vick was scheduled to sign copies of his autobiography, “Finally Free,” at Barnes and Noble stores in Atlanta, New Jersey and Pennsylvania until receiving threats in connection with his past involvement in a dog fighting ring, for which he served time in prison.

“We cannot knowingly put anyone in harm’s way,” Byron Williamson, president of Worthy Publishing, told Phillymag.com’s Tim McManus, “and therefore we must announce the cancellation of Mr. Vick’s book-signing appearances.”

Vick spokesman Chris Shigas said the threats, first reported by McManus, were “very disturbing.” Since his release from prison, Vick has spoken publicly at Humane Society events. “We understand that a lot of people out there will never forgive him,” Shigas said (via Philly.com’s Les Bowen). “But at what point do we say a line has been crossed?”

McManus writes that “there has been a recent uptick in what a source close to Vick calls ‘credible threats of violence.'” Last fall, it was revealed that he was again a dog owner and Vick said then in a statement:

“I understand the strong emotions by some people about our family’s decision to care for a pet. As a father, it is important to make sure my children develop a healthy relationship with animals. I want to ensure that my children establish a loving bond and treat all of God’s creatures with kindness and respect. Our pet is well cared for and loved as a member of our family.”

Vick last month agreed to a restructured three-year deal to remain with the Eagles, with whom he signed in 2009 after missing two seasons while serving his prison sentence.

Vick did not address the threats or the cancellation, but tweeted this morning:

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