Grisaffi said he's been replaying the ordeal in his mind.
"Rick risked his life," said Grisaffi, 61, of Laguna Beach, Calif. "Did I do enough? Should I have grabbed my fins and swam out with him?"
The head of the state Department of Land and Natural Resources, the agency responsible for Hawaii's waters, said he was deeply saddened to learn of Lutterop's death and joined Hawaii's people in extending his sympathy to her family and friends.
"As an island state, we are aware that we are all visitors in the natural environment that surrounds us, and that unfortunate incidents such as this one can occur," William Aila said. "We are committed to furthering research efforts that will help guide effective management actions in the interest of safety."
Hawaii officials announced Tuesday they plan to spend the next two years studying tiger shark movements around Maui amid what they call an unprecedented spike in overall shark attacks since the start of 2012.
There have been eight attacks statewide this year and 10 in 2012. Hawaii usually sees only three to four attacks each year.
The last time someone in Hawaii died from a shark attack was in 2004, when a tiger shark bit Willis McInnis in the leg while he was surfing 100 yards off Maui. McInnis suffered severe blood loss and died on the shore despite rescue efforts by beachgoers, police and paramedics. The last fatal attack before that was in 1992.
A woman was killed last month after being attacked while swimming in Brazil during her vacation.
Worldwide, there were seven deaths resulting from unprovoked shark attacks in 2012, including one in California, according to the Florida Museum of Natural History at the University of Florida.
Associated Press writer Oskar Garcia contributed to this report.
Follow Jennifer Sinco Kelleher at http://www.twitter.com/jenhapa .