Paul David Blackburn, 56, of Illinois, disappeared while snorkeling near the Molokini Crater off Maui on the evening of June 11, 2013. His son saw him go beneath the water’s surface at about 5:30 p.m. and he never resurfaced. He was wearing a white rash guard and board shorts and was not using a life jacket.

The United States Coast Guard, the Maui County Fire Department and other local agencies conducted an extensive air and sea search that included helicopters, a response boat and a Coast Guard cutter. Mariners were alerted and the search covered more than 448 square miles before active operations were suspended. No trace of Blackburn was found, and his disappearance is classified as a lost or injured missing person case; he is presumed to have drowned.

Did anyone on Maui or who was on the water near Molokini on June 11, 2013, see anything that could help clarify what happened that evening?