Collins maintained his innocence and called the charges against him "meritless," according to The Associated Press.
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Saturday's news is an about-face for the congressman, who vowed to continue his campaign for re-election earlier this week after charges were announced.
Prosecutors contend that Collins, his son Cameron Collins, and Stephen Zarsky, the father of Cameron Collins’ fiancee, engaged in illegal practices related to dumping their stock in an Australian company after clinical trials on an important medication failed.
Prosecutors state that Collins and the two others used nonpublic information about the results of a drug trial to avoid over $768,000 in losses they would have incurred if they traded the stock after the drug trials became public.
The three men are facing charges of conspiracy, wire fraud and other counts.
Collins was the first sitting member of Congress to endorse Trump's presidential bid, CNN reported.
The 68-year-old three-term incumbent represents New York’s 27th Congressional District, which includes Buffalo and Rochester.