Alexander Imich, who at age 111 was declared to be the oldest man in the world, died peacefully on Sunday morning.

According to CBS News, his niece, Karen Bogen of Rhode Island, revealed that Imich died Sunday at his home in Manhattan around 9 a.m.

She said that she had visited the retired chemist and parapsychologist a day earlier. She also noticed that his health declined about two weeks ago, and he no longer recognized her.

Imich was born on Feb. 3, 1903, in Poland. In 1939, he left Poland when the Nazis invaded Germany and eventually settled in the U.S. in the 1950s with his wife who died in 1986.

As a scholar of the occult, he published a book on paranormal activity at age 92, the New York Times reported.

During an interview with WABC-TV last month, Imich talked about the secret to his longevity, revealing that he was athletic in his younger days and gave up smoking. He also attributed some of his health to a healthy diet consisting of chicken, fish and no alcohol. Plus, he took up swimming as a younger man.

He downplayed his long life in an interview with NBC 4 New York Monday, saying, "I don't know. I simply didn't die earlier. I have no idea how this happened."

Despite being a supercentenarian, Imich said that he has yet to figure out all of life's answers and that he still had one burning question: "I wanted to understand the universe and myself in it."

Imich, however, was not the oldest person in the world. The oldest person is 116-year-old Misao Okawa of Japan, according to the Gerontology Research Group, reported USA Today.

Guinness is investigating the claim that Sakari Momoi, 111, of Japan is now the oldest man in world.

The Polish immigrant lived in New York City's Upper West Side until his death.