A federal probe into an alleged fraud impacting National Football League players has broadened in scope, with the Federal Bureau of Investigation asking for information from athletes leaguewide.

The NFL Players Association on Friday sent its members a notice from the FBI seeking details about investments with Mohamed Coulibaly, the deceased founder of an e-commerce business that targeted professional athletes.

The email from the NFLPA, the league's labor union, was sent to "all active and former players," according to a copy of the message viewed by Barron's. It seeks "to identify witnesses and investors in The Vent Motion LLC," the registered name of Coulibaly's enterprise.

An FBI spokesperson didn't respond to messages seeking comment.

A person familiar with the NFLPA's response to the alleged scam says the organization is seeking to keep players informed, while providing support to its members impacted by the situation.

Coulibaly's alleged scheme, first reported by Barron's , has attracted widespread attention because of the roster of pro athletes that he had claimed as investors. Former Arizona Cardinals general manager Steve Keim served as Coulibaly's operations chief.

An attorney for Keim said in a statement to Barron's that the former team executive spoke in early August with FBI agents, who told him that he is regarded as a victim of the scheme and not a subject or a target of any investigation.

Tom Simon, a former FBI special agent specializing in financial crime who now works as a private investigator in Jacksonville, Fla., says the agency's broad outreach indicates a large-scale investment-fraud investigation.

"One of the things it tells me is that there's a lot of victims and there's a high dollar amount lost," he says.

Coulibaly was found dead on July 31 in the swimming pool of a Harrison Township, N.J., home. No cause has been released for the 24-year-old's death, which is being investigated in connection with a criminal probe, Barron's has reported.

Coulibaly had told investors that they were buying ownership of Shopify-powered web stores, which purportedly sold items such as motorized water guns, hand-held electric fans, and smartphone cases.

He then provided the shop owners with login credentials to track activity on the stores' internal dashboards. Those sales data were apparently falsified by using a manual entry feature built into Shopify's software, Barron's reported.

"According to public reporting, Mohamed Coulibaly solicited investors in The Vent Motion," the FBI wrote in its notice distributed by the NFLPA. "Reporting indicates that investors did not realize profitable returns and that much of the sales data may have been fabricated."

The notice provides a link to an online questionnaire for investors to complete with their contact information and amount and timing of investments.

Athletes who lost money investing with Coulibaly including former New York Giants linebacker Tae Crowder have told Barron's that they were interviewed by agents with the FBI in recent weeks.