The Eric Trump Foundation was founded in 2007 to raise money for St. Jude Children's Research Hospital in Memphis, Tennessee, a nonprofit institution that cares for children with cancer and other serious diseases.
The foundation organized annual golf tournaments on a course owned by Eric's father, the Trump National Golf Club in Westchester County north of New York.
In the event's early years, the use of the course was donated by the Trump Organization, headed by the future president.
Using the donated facilities allowed the foundation to send most of the funds raised to the hospital, Eric Trump told donors.
But starting in 2010, the Trump Organization billed the foundation for use of the club, according to a Forbes magazine investigation.
While the cost of organizing the one-day tournament was at first less than $50,000, it soared in later years, reaching $322,000 in 2015, according to tax filings seen by the magazine's reporters.
Expenses at that level "defy any reasonable cost justification for a one-day golf tournament," according to golf event experts cited in the article.
WATCH: The moment Donald Trump crashes a wedding in New Jersey
It quoted two people directly involved in the matter as saying the person who commanded that the Trump Organization start billing hundreds of thousands of dollars was Donald Trump himself.
Forbes said Eric Trump told its reporters that the cost of running the tournament was around $100,000 -- raising questions about the gap between that amount and the $322,000 listed in tax papers for 2015.
New York Attorney General Eric Schneiderman has opened an investigation to clarify matters, a spokesman told AFP on Sunday.
In late 2016, the young Trump ended his own direct involvement in the foundation, which he said would be restructured and renamed, under new leadership, in a move to avoid any conflict of interest after his father's election as president.
The magazine did note that over the years Eric Trump's foundation had done "a ton of good," raising more than $11 million for the children's hospital, mostly through the golf event.
