Sources say Mourginakis was subject to mounting professional and personal turmoil over recent months.
He controlled the Stamford-based Oceania Maritime Agency that worked in tandem with Seatrade Compania Maritima SA of Piraeus.
At his death the fleet had dwindled to five tankers and a bulk carrier.
Like other Greek owners Mourginakis is said to have suffered losses from investments in the Russian bond market.
