Read more about this story from CNN affiliate WTOV.

(CNN) -- Federal authorities say they have arrested a fugitive in rural Florida who was on the lam for 30 years after faking a heart attack to escape from prison.

A handwritten document buried in a file led cold case investigators to Ian Jackson MacDonald, 71, the U.S. Marshals Service said in a statement. They arrested him Tuesday in Homosassa, Florida.

"I was told that he just let out a big sigh and said, 'Yeah, you're right -- you got me,'" U.S. Marshals senior Inspector Barry Golden told CNN affiliate CBC News.

Authorities allege that MacDonald, who went by the nickname "Big Mac," faked a heart attack while he was in a federal prison in South Miami-Dade County in 1980. He later escaped from a hospital, the U.S. Marshals said.

MacDonald had been awaiting extradition on a Canadian warrant to face outstanding charges for allegedly smuggling 500 pounds of marijuana.

After less than a day in the hospital, he persuaded a security guard to unshackle his legs so he could take a shower, the U.S. Marshals said in a statement.

"The security guard walked to the nurse's station, and when he returned, MacDonald was gone," the statement said.

People in Pennsylvania and West Virginia knew MacDonald by a different name -- Jack Hunter, CNN affiliate WTOV reported.

U.S. Marshals allege that MacDonald and his wife changed their names and moved to southwest Pennsylvania after he escaped from custody. He owned a store in nearby West Virginia, "19th Hole Used Appliances," WTOV said.

"It's really surprising that someone can live in your neighborhood for that long undetected," resident Jim Lyle told WTOV.

Investigators in Pennsylvania learned that MacDonald and his wife were living in a Florida mobile home they had purchased in 2009. Authorities there arrested him outside the home Tuesday.

"I have been looking over my shoulder all these years. I wondered when this day would come," MacDonald reportedly told investigators, the U.S. Marshals said.

According to the U.S. Marshals, Canadian authorities said their arrest warrant for importation of marijuana was still active, and MacDonald could still face charges in Canada.