Robert Pittenger founded his namesake real estate company three decades ago but transferred the company to his wife after he was elected to Congress in 2012 to meet House ethics rules. Over the years, PLI identified raw tracts in potential growth areas and gathered investors to buy the properties, which were held by limited liability companies. The goal over time was to make a return by selling the properties to developers. As manager, PLI also collects annual fees from investors for property taxes and other expenses. Some investors have said they are unhappy with the way PLI has handled their investments, with some questioning the slow pace of land sales and the transparency of the company’s operations. The Observer also reported in August that some investors were surprised by markups that PLI applied to the tracts before selling them to the LLCs. PLI has said the business has a successful track record and is taking steps to sell the properties. Robert Pittenger has said the markups were standard procedure and fully disclosed. In their investigation, FBI and IRS agents have interviewed investors, congressional staffers and other people familiar with Pittenger’s role at the company, the Observer has reported. The interviews have continued in recent weeks, with agents talking with at least two additional investors, sources told the Observer, speaking on the condition of anonymity because of the sensitive nature of the investigation. In one of the interviews, the agents asked about markups that PLI applied to land purchased by its investors as well as any communication the investor had had with Robert Pittenger, one of the sources said.