GODFREY, Ill. (AP) – Neighbors said Monday they had never seen anything to explain why Edward Van Dyk would toss his two sons, ages 4 and 8, from the 15th floor of a Florida hotel and jump to his own death.

In fact, a year after the cancer specialist and his family moved into a gated subdivision of sprawling, tree-shaded brick-and-stone homes, Barbara Maggos said she and other neighbors never got to know him, his wife and their boys. “We may never know,” Maggos said of the reason for the deaths.

Neighbor Dorothy Mottaz said she didn’t see much of the Van Dyks, aside from hearing the children play in their backyard or seeing their mother, Qinuo Van Dyk – a fertility doctor who sidelined her career to stay at home as her husband pursued his – at the supermarket.

“It was such a shock doing something like that to young children. That’s the hardest part,” Mottaz said.

Investigators said Van Dyk left no suicide note, leaving no clues for investigators, neighbors, and Van Dyk’s wife and other relatives.

To Maggos, “the man had to have snapped.” Van Dyk’s father, Oebele, said he believes as much, speculating Monday that his son might have killed his boys Saturday out of temporary insanity.

Oebele Van Dyk said his son seemed delusional when the two spoke by telephone Thursday – the day before Edward Van Dyk joined his family in Miami Beach.

Van Dyk’s wife, Qinuo, told police that although the couple had marital problems over the past six months, their relationship had improved and the family was at the hotel in Florida to celebrate the couple’s 10th wedding anniversary, Miami Beach police spokesman Bobby Hernandez said. She told police she heard one of her children scream before she emerged from the hotel room’s bathroom and saw her husband leaping from the balcony.

Illinois authorities seized Van Dyk’s computer from the family home in Godfrey, about 30 miles northeast of St. Louis. There was no word Monday whether the computer held any useful information, Hernandez said.

Sheriff’s investigators in Madison County, Ill., did not immediately return calls seeking comment.

“Without a suicide note we can have 100 theories, but none is 100 percent,” Hernandez said. “This might never be explained 100 percent.”