DOVER, De. (CBS) — Convicted in 2008 of mutilating and killing 19 cats in Central Jersey, 58-year-old Anthony Appolonia now lives in Dover, Delaware, where neighbors believe that he’s up to no good.

No one answered the door at Appolonia’s home, but his next door neighbor says she’s seen people drop off pets to his apartment in the past. “It was a young girl and guy in a small car and they had a cage. They took it in with some food and they left. And I never seen them come back and pick it up.”

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Posted warning signs on Craigslist say Appolonia has answered online ads for free cats, sometimes meeting people at his home.

In other cases, Appolonia would meet people with cats to adopt at public places like McDonald’s in the Dover area.

“I met him near the McDonald’s near the AFB. He came with his cat carrier,” said Alicia Dobies.

At first, Dobies says she believed why Appolonia wanted to adopt her cat Harley. “He was telling me how his therapist was telling him it would be a good idea for him to have a cat that eases his anxiety,” she said.

“I thought that was sweet. A lot of people want kittens, not grown cats, so we were happy.”

Then, her husband saw the warnings on Craigslist. “With the stories about what happened in Jersey, I’m afraid she might be dead,” Dobies said.

Appolonia is banned from owning pets in New Jersey, but the same restriction doesn’t apply in Delaware. A spokesperson for the Delaware Office of Animal Welfare would only confirm there is an open investigation into whether Appolonia has abused or killed cats in this state as well.

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Neighbors say they’ve seen agents on his property. “They were looking through all the trash cans and all and had their gloves on, but I don’t think they found anything,” one neighbor said.

The bottom line here, if you are planning to put your pet up for adoption, experts say it’s best to know who you’re giving your furry friend to. “It takes some effort,” said Kevin Usilton, the executive director at FSAC and SPCA. “Put it on your Facebook page. Ask your friends and family do you know anyone that is looking for a pet that can accept my pet, because often times then, you can have a connection and make sure that person is not a serial cat killer.”