San Francisco, Aug 31 : Federal prosecutors in the US are probing personal benefits Tesla allegedly paid to its CEO Elon Musk in order to build a lavish 'glass house' for him. The Department of Justice (DoJ) and the Securities and Exchange Commission (SEC) are investigating the use of Tesla funds to bankroll a secret project -- known internally at Tesla as 'Project 42' -- for Musk, reports the Wall Street Journal. 'Manhattan federal prosecutors are investigating Tesla's use of company funds on a secret project that had been described internally as a house for Chief Executive Elon Musk,' the report said late on Wednesday, citing people familiar with the matter. According to the report, Project 42 involves a large glass structure to be built in Austin, Texas, for Musk. The US Attorney's Office for the Southern District of New York has reportedly sought information about what benefits have been paid to Musk, how much Tesla spent on the project, and what the project was for, the report mentioned. The SEC has also opened a civil investigation into Tesla's 'Project 42'. Earlier reports in July mentioned that Musk once planned a lavish glass house for himself near Tesla headquarters in Austin, Texas, worth millions of dollars. The secret project included renderings of a glass box with residential features, such as bedrooms, bathrooms and a kitchen, reports claimed. The project reportedly triggered an internal probe over "possible improprieties", over concerns that Musk might be using company funds to build the house. There was a waterfall incorporated into the structure's surrounding landscape in addition to a futuristic pickup truck. The concepts for the house included either a "twisted hexagon" or a glass cube reminiscent of Apple's 5th Avenue store. Musk recently disclosed he lives in a tiny $50,000 rented home in Boca Chica/Starbase, near Space X's facility. /IANS