He is accused of two counts of wire fraud, and allegedly defrauding more than a dozen investors out of more than $2 million.
It is also not actually clear whether CrossFit actually counted Newman as a founder.
A statement from the FBI says Newman was a "self-styled entrepreneur" who juggled projects including a venture capital firm, called Outlier Capital, as well as a film production company that tried and failed to assemble a project on the New York Yankees.
From 2012 through this year, according to the complaint, Newman made a number of misrepresentations as he tried to raise funds for CrossFit businesses. He also used funds for personal expenses - "including paying back others who invested in his prior projects," the FBI said in a statement.
According to the US Department of Justice, "even after his partners removed him from one of the CrossFit companies because of suspected fraudulent activity and willful misconduct, Newman continued to solicit investments on behalf of the company that he used for personal expenses."
Other allegations include Newman falsifying information to convince investors one his ventures had already raised millions in funding, and that he sent a picture of a wire transfer for $165,000 that was a fabrication.
Judging by his social profile, Newman left CrossFit in November of last year, and launched a competing business called Northstar CrossFit in December 2014. The company's website does not list any employees, but it does have a page for potential candidates to apply for jobs.
CrossFit, not to be confused with Northstar CrossFit, did not immediately respond to a request seeking comment.