Greg Epker knows how his wife killed their four children and herself, but he doesn't know why - and authorities say he likely never will.

The family had some financial problems, but chances are "pretty strong" the motive will never surface, said Sheriff Robert Nall."He's completely mystified. . . . He can't understand it either," Nall said of Epker, who was hospitalized for shock after he discovered the grisly scene upon returning to the family home from his job at a sign company in nearby Quincy.

Police pieced together the chain of events on Thursday, a day after the murder-suicide rocked this western Illinois town of 1,000 in the rolling farm country about 140 miles northwest of St. Louis.

First, Sheila Epker drowned her oldest daughter, Casey, 8, in a bathtub. Then she placed pillows and blankets on the kitchen floor, making beds for her three other children to die in, and turned on the gas stove.

When the gas proved too slow a method, the 27-year-old housewife marched her children - dressed in their Sunday best - into the living room one by one, sat them on a couch and shot each in the head.

Then she, too, sat on the couch and took her own life with the same gun.

Nall said Mrs. Epker had no history of mental problems, nor had she shown any signs of alcohol or drug abuse. He acknowledged they had financial problems, but "no more than any other young family."

But the Quincy Herald-Whig reported Thursday that St. Mary Hospital had sued the Epkers over $3,900 in bills accumulated since 1980. The hospital won the judgment and Epker's wages were docked Dec. 28, the newspaper said.

"There's a lot of speculation and there are a lot of ways to go with it," Nall said.