[2] Prior to moving to the United States, Dekkers was accused by former business partners of defrauding them of tens of thousands of guilder.
[6] For a short while, during their time at the school, both Marwan and Atta lived with a company employee named Charlie Voss.
Dekkers also maintained that he did not feel guilty and he had made copies of their passports and their visas, but he said there were no red flags asserting "Nothing was out of the ordinary.
[2] In January 2002, Huffman Aviation again made headlines when the local paper sent a reporter onto its property, who managed to casually move between airplane cockpits, fuel tanks, and other "safety concerns" without anybody noticing or stopping him.
In March, the school was cited for having left fuel trucks unlocked, with keys in the ignition, at the Venice Municipal Airport.
On February 24, 2002, Dekkers suspected someone tried to have him killed when piloting a helicopter he crashed into the Caloosahatchee River as the fuel lines were cut.
After the attacks, he wound up losing four hundred thousand dollars, and most of his students who were primarily international later dropped out.
A second school he operated in Naples, Florida, was closed after he was sued by a former business partner after defaulting on a series of loans, one of which accounted for $1.7 million.
However, Dekkers and his employees described Atta as "dead man walking" due to his "white face and no emotions and was a nasty person, very unfriendly".
"[13] Dekkers stated in 2016 that his "9/11" began on the morning of September 12 and that he no longer considers each year since the attack to be an anniversary rather he "lives 9/11 every day.
"[9] In 2007, Dekkers sold swimming pools while living in a villa in a gated community in Fort Myers, Florida.
A year later the 2007–2008 financial crisis resulted in the Great Recession causing the Florida housing market to collapse, and he lost his business.
[2] In 2011, Dekkers published an autobiography, Guilty by Association, detailing his life, passion for flying, and his interactions with Atta and al-Shehhi.
"[13] On December 2, 2012, Dekkers was arrested on federal drug charges by the United States Department of Homeland Security in Houston after accepting a blue suitcase containing 18.7 kilograms of cocaine and 860 grams of heroin.
[9] On April 11, 2019, Dutch authorities arrested Dekkers at Amsterdam Airport Schiphol with 118 swallowed scoops of cocaine.