"All of our competitors in the breed are good people," Chaffin told ABC News. "I don't think it was someone in the dog world. There are lots of crazy people out there."
A representative for People for the Ethical Treatment of Animals, which has sent people to Westminster in past years, brushed aside Chaffin's suspicion that an "animal rights activist" could have been responsible for Cruz's death.
"The accusation is ludicrous and he hasn't even identified the person as an animal rights activist," Lisa Lange, senior vice president at PETA told ABC News. "It was someone at the dog show who criticized him."
Lange said, in a statement to ABC News, that PETA protested at Westminster, in part, against what it sees as the glamorization of pure-bred animals.
"(M)ore than 7 million cats and dogs are entering U.S. shelters every year with half of them being euthanized due to a lack of good homes – homes that are filled with dogs from breeders and puppy mills because of Westminster. There's no excuse for breeding more dogs while homeless mutts (and purebreds) are literally dying for homes."
Blue said the show provides dog owners the option to hire security guards during their stay in New York, a sign that "it could be a dangerous situation." The owner was more open, however, to the possibility of other motivations.
"It could be some crazies or some animal rights fanatics," she said. "Or it's always possible -- he was a top-winning dog, so it's always possible, those things have happened -- that other people in the dog show world try to knock out top competition. ... You just don't know."
Chaffin criticized the Westminster Dog Show for lack of security.
"If I could do it all over again, I wouldn't go to Westminster," he said. "I won't go to that show again. It's not safe for dogs."
Westminster, in a statement issued to ABC News today, said, "We have never, to our knowledge, had an incident at our show where a dog has become ill or was harmed as a result of being poisoned.
"We are ultra cautious to the point where we do not allow dogs to be off lead at any time while at our show," the statement read. "Unfortunately, no autopsy was performed, so there are a lot of unanswered questions. No other animal which attended our show was reported to our show veterinarians with any incident of serious illness. We have been made aware that no rodent poison is used at the Piers and pest control is maintained through trapping."
Cruz, who did not place at Westminster, held the designation of "Grand Champion," a title given to dogs earning a total of 25 points with three major wins at other shows. Cruz had competed in at least 30 other dog shows over the past year, according to Blue.
After Cruz's death, the owner of a fellow competitive dog, not in Cruz's breed, came forward to offer a $2,000 reward for "any information that could lead to the arrest of the person who might of done this to Cruz," calling the possible poisoning a "worst nightmare."
Blue said she filed a complaint with the New York Police Department last week but is still awaiting a follow up call from the agency. A representative for the NYPD told ABC News it can find no record of a complaint filed by Blue.
"People just need to know they need to be aware of where their dogs are," said Blue. "This thing has just left a hole in my heart. It has taken some of the joy and fun out of showing and raising dogs. It's something I'll never get over."
ABC News' Lauren Effron contributed to this report.