Mother Jones reported this story way back in 2011. That was a rough year for Trump’s credibility, the year he said he talked to Putin (but recently said he had never met or talked to Putin) and the year he said that if he ran for President he would release his net worth statement.
Also in 2011, Jerome Corsi stated that Donald Trump had told him that he had gotten his own computer expert to look at Obama’s birth certificate, and that the expert concluded that it was computer-generated (a Xerox Workcentre 7655 multifunction office machine is a computer of sorts). Corsi described the conversation in more detail in an interview with Alex Jones, but Trump claims that he never discussed this topic with Corsi, and the only conversation he had with Corsi was to wish him well on his new book (which Trump says he hadn’t read). More recent revelations from WorldNetDaily publisher Joseph Farah as reported in the New York Times suggest that Trump reached out to Farah and Corsi on a continuing basis.